Dry adhesives comprised of micropores and nanopores

ABSTRACT

A dry adhesive comprising a micro-featured and nano-featured surface, and a compliant surface having a hardness of about 60 Shore A or less, the micro-featured and nano-featured surface and the compliant surface being capable of forming upon contact a dry adhesive bond with each other.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit, under 35 U.S.C. §119(e), of thefollowing U.S. provisional applications:

-   -   U.S. provisional application Ser. No. 61/485,700, filed on May        13, 2011,    -   U.S. provisional application Ser. No. 61/486,382, filed on May        16, 2011,    -   U.S. provisional application Ser. No. 61/486,951, filed on May        17, 2011,    -   U.S. provisional application Ser. No. 61/499,864, filed on Jun.        22, 2011, and    -   U.S. provisional application Ser. No. 61/566,777, filed on Dec.        5, 2011.        All documents above are incorporated herein in their entirety by        reference.

FIELD OF THE INVENTION

The present invention relates to dry adhesives.

BACKGROUND OF THE INVENTION

Metals, glass, and plastics are common fabrication materials used inmany commercial and industrial applications. The surfaces of thesematerials have a wide range of finishes. The finish of these surfacesdefines the texture of the material, which ranges from a highly polishedsurface to a visually and/or tactilely rough surface. Further, theaforementioned materials are non-tacky (i.e. non adhesive) and requirethe use of an adhesive to adhere one surface of the material to theother.

Inspired by the ability of the gecko to adhere to most surfaces at anyangle, attempts at developing dry adhesives mimicking the spatula tippedsetae on the gecko feet pads have been carried out at many institutions.Geckos can instantaneously and repeatedly attach and detach theirfibrillar feet pads to a wide range of surfaces without leavingresidues. Typical approaches to produce such a dry adhesive haveconsisted in designing and fabricating synthetic gecko setae. However,the gecko's setae have a complicated branched structure. A single geckomay have two millions setae on its feet. Each seta may branch intohundreds of spatula-shape tips. These spatula-shape tips are about 200nanometers in diameter. It is believed that the adhesive force of thegecko feet pads results from the cumulative effect of van der Waalsforces between the millions of setae on the feet pads in intimatecontact with the surface the gecko is climbing on.

On another subject, inkjet printers have become ubiquitous and anindispensible tool in homes and small offices. Inexpensive inkjetprinters typically employ water-based inks to print on uncoated orcoated paper. The quality of images printed on coated paper with aninkjet printer has exceeded the visual threshold and can thus competewith photographic silver halide processes.

However, there are a number of problems and/or disadvantages associatedwater-based inks. A first problem is that these inks are water soluble.Therefore, the images printed with such inks may not be waterfast. Asmall drop of water can cause severe smearing of the information on theprinted image. The smeared image may often be irrecoverably damagedand/or information on the image may be permanently lost.

Another problem associated with images printed with inkjet printers isarchival. Images printed with inkjet printers have a limited lifetimedue to low lightfastness of the inks involved. Dye based inks tend tofade in a relatively short time. Further, each color has a tendency tofade at a different rate leading to a change in the image color balance.

In the prior art, waterfastness and/or lightfastness have been improvedby using solvent based inks. Such inks are not water soluble, and theimages they produce thus tend to be waterfast and lightfast. However,the main components in solvent ink are volatile organic compounds (VOC).These VOCs make these inks less environmentally friendly.

A more environmentally friendly solution is to laminate a protectivefilm over the printed image. Laminating films are available as thermallyactivated film and/or pressure sensitive, heatless film. Thermallyactivated films typically contain a heat-activated adhesive and areapplied using a heated roll laminator to irreversibly bond the film tothe substrate. In such hot melt lamination processes, the thickness ofthe laminating film is limited by heat transfer constraints. This isbecause polymers used to make these films typically are thermalinsulators that do not conduct heat very well. Thus the thickness of thefilm will be limited as only films that are thin enough to allowsufficient heat transfer to melt the adhesive layer can be used.Pressure sensitive film contains a pressure sensitive adhesive (glue)that is protected with a backing film that does not adhere to the glue.When the backing film is removed, the pressure sensitive adhesive layeris applied with a cold roll laminator to irreversibly bond to the filmto the substrate via the glue.

A disadvantage of such laminating films is that complex laminatingequipments is typically required to apply the required heat and/orpressure in order to adhere the laminating film to the printed image.Further, the bond between the printed image and laminating film isgenerally permanent and thus the laminating film may not be readjustedor removed once the lamination process is completed.

The present description refers to a number of documents, the content ofwhich is herein incorporated by reference in their entirety.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided:

1. A dry adhesive comprising:

-   -   a. a micro-featured and nano-featured surface, and    -   b. a compliant surface having a hardness of about 60 Shore A or        less, the micro-featured and nano-featured surface and the        compliant surface being capable of forming upon contact a dry        adhesive bond with each other.        2. The dry adhesive of item 1, wherein the compliant surface has        a hardness of about 55, 50, 45, 40, 35, 30, 25, 20 Shore A or        less.        3. The dry adhesive of item 1 or 2, wherein the compliant        surface is a surface of an object made of a compliant material.        4. The dry adhesive of item 1 or 2, wherein the compliant        surface is a layer of a compliant material alone or on a        support.        5. The dry adhesive of item 1 or 2, wherein the compliant        surface is comprised of spots of a compliant material on a        support.        6. The dry adhesive of item 4 or 5, wherein the support has a        polymeric surface, such as a surface made of PET, a paper        surface, a metallic surface.        7. The dry adhesive of item 5, wherein the support is the        micro-featured and nano-featured surface, the dry adhesive        thereby being self-adhesive.        8. The dry adhesive of any one of items 3 to 7, wherein the        compliant material is a polymer.        9. The dry adhesive of item 8, wherein the polymer is a        thermoplastic elastomer or a crosslinked elastomer.        10. The dry adhesive of item 9, wherein the polymer is a silicon        elastomer, a silicon rubber, a styrene-isoprene elastomer, a        styrene-butadiene elastomer, a styrene-ethylene/butylene-styrene        elastomer, a styrene-ethylene/propylene-styrene elastomer, an        ethylene-butadiene-styrene elastomer, a siloxane polymer, or a        poly-isocyanate.        11. The dry adhesive of any one of items 1 to 10, wherein the        compliant surface and/or the micro-featured and nano-featured        are backed with a conventional adhesive.        12. The dry adhesive of any one of items 1 to 11, wherein the        micro-featured and nano-featured surface has a roughness average        in amplitude (R_(a)) ranging between about 0.2 μm and about 3.0        μm, between about 0.2 μm and about 1.5 μm, between about 0.25 μm        and about 1.5 μm or between about 0.2 μm and about 0.7 μm.        13. The dry adhesive of any one of items 1 to 12, wherein the        micro-featured and nano-featured surface has a mean spacing of        profile irregularities (RS_(m)) between about 20 μm and about        2000 μm, between about 20 μm and about 1500 μm, between about 20        μm and about 1000 μm or between about 20 μm and about 500 μm.        14. The dry adhesive of any one of items 1 to 13, wherein the        micro-featured and nano-featured surface is a metallic surface,        a glass surface, a paper surface, or a polymeric surface, the        metallic surface, glass surface, paper surface and polymeric        surface bearing micro-features and nano-features.        15. The dry adhesive of any one of items 1 to 13, wherein the        micro-featured and nano-featured surface is comprised of        micro-featured and nano-featured spots on a support.        16. The dry adhesive of item 15, wherein the support has a        metallic surface, a glass surface, a paper surface, a polymeric        surface.        17. The dry adhesive of item 16, wherein the support is made of        aluminum.        18. The dry adhesive of item 16, wherein the support is an        inkjet photo paper.        19. The dry adhesive of item 16, wherein the support is a        polyethylene phthalate or a vinyl sheet, such as a PVC sheet.        20. The dry adhesive of any one of items 1 to 6 and 8 to 13,        wherein the micro-featured and nano-featured surface is        comprised of micro-featured and nano-featured spots on a        support, the support being the compliant surface, the dry        adhesive thereby being self-adhesive.        21. The dry adhesive of any one of items 1, 2, 5, 6, 8 to 13,        and 15-19, wherein the micro-featured and nano-featured surface        is comprised of micro-featured and nano-featured spots deposited        on a support and wherein the compliant surface is comprised of        spots of a compliant material deposited elsewhere on said        support, the dry adhesive thereby being self-adhesive.        22. The dry adhesive of item 21, wherein the support is a        plastic surface, such as a surface of a PET film, a metal        surface, or a paper surface that is optionally backed by a        plastic layer.        23. A micro-featured and nano-featured surface for the dry        adhesion of a compliant surface having a hardness of about 60        Shore A or less, the micro-featured and nano-featured surface        being able to form upon contact a dry adhesive bond with the        compliant surface.        24. The micro-featured and nano-featured surface of item 23,        wherein the micro-featured and nano-featured is as defined in        any one of items 1 and 11 to 19 and/or the compliant surface is        as defined in any one of items 1 to 6 and 8 and 10.        25. A compliant surface having a hardness of about 60 Shore A or        less for the dry adhesion of a micro-featured and nano-featured        surface, the compliant surface being able to form upon contact a        dry adhesive bond with the micro-featured and nano-featured        surface.        26. The compliant surface of item 25, wherein the micro-featured        and nano-featured is as defined in any one of items 1 and 11 to        19 and/or the compliant surface is as defined in any one of        items 1 to 6 and 8 and 10.        27. Use of a micro-featured and nano-featured surface according        to any one of items 1 and 11 to 19 as a substrate for the dry        adhesion of a compliant surface according to any one of items 1        to 6 and 8 and 10.        28. Use of a compliant surface according to any one of items 1        to 6 and 8 and 10 as a substrate for the dry adhesion of a        micro-featured and nano-featured surface according to any one of        items 1 and 11 to 19.        29. A dry self-adhesive comprising:    -   a. a micro-featured and nano-featured surface, and    -   b. a compliant surface having a hardness of about 60 Shore A or        less, the micro-featured and nano-featured surface and the        compliant surface being capable of forming upon contact a dry        adhesive bond with each other, wherein the micro-featured and        nano-featured surface and the compliant surface each occupy one        or more area(s) of a same physical surface.        30. The dry self-adhesive of item 29, wherein the micro-featured        and nano-featured surface and the compliant surface each occupy        one area of the same physical surface        31. The dry self-adhesive of item 29, wherein the micro-featured        and nano-featured surface and the compliant surface each occupy        multiples discrete areas of the same physical surface.        32. The dry self-adhesive of item 29 or 31, wherein the area(s)        range(s) in size from about 1 μm to about 5 mm.        33. The dry self-adhesive of any one of item 29 to 32,        comprising one or more compliant area(s) deposited on a        micro-featured and nano-featured surface.        34. The dry self-adhesive of item 33, wherein the micro-featured        and nano-featured surface is a metallic surface, a paper        surface, or a polymeric surface.        35. The dry self-adhesive of item 33, wherein the metallic        surface is an aluminum surface.        36. The dry self-adhesive of item 33, wherein the paper surface        is an inkjet photo paper.        37. The dry self-adhesive of item 33, wherein the polymeric        surface is a polyethylene phthalate or a vinyl surface, such as        a PVC surface.        38. The dry self-adhesive of any one of items 33 to 37,        comprising multiple discrete compliant areas spaced apart on the        micro-featured and nano-featured surface.        39. The dry self-adhesive of item 38, where the ratio of the        total area occupied by the compliant areas to the total area        occupied by the micro-featured and nano-featured surface in the        spaces between the compliant areas is 1:1.1 or more.        40. The dry self-adhesive of any one of item 29 to 32,        comprising one or more micro-featured and nano-featured area(s)        deposited on a compliant surface.        41. The dry self-adhesive of items 40, comprising multiple        discrete micro-featured and nano-featured areas spaced apart on        the compliant surface.        42. The dry self-adhesive of item 41, where the ratio of the        total area occupied by the micro-featured and nano-featured        areas to the total area occupied by the compliant surface in the        spaces between the micro-featured and nano-featured areas is        1:1.1 or more.        43. The dry self-adhesive of any one of item 29 to 32, wherein        one or more micro-featured and nano-featured area(s) and one or        more compliant area(s) are deposited on a surface of a support.        44. The dry self-adhesive of item 43, wherein the surface of the        support is a plastic surface, such as a surface of a PET film, a        metal surface, or a paper surface that is optionally backed by a        plastic layer.        45. The dry self-adhesive of any one of items 29 to 44, being        backed with a conventional adhesive.        46. The dry self-adhesive of any one of items 29 to 45, wherein        the compliant surface has a hardness of about 55, 50, 45, 40,        35, 30, 25, 20 Shore A or less.        47. The dry self-adhesive of any one of items 29 to 46, wherein        the compliant surface comprises a polymer.        48. The dry self-adhesive of items 47, wherein the polymer        comprised in the compliant surface is a thermoplastic elastomer        or a crosslinked elastomer.        49. The dry self-adhesive of items 48, wherein the polymer        comprised in the compliant surface is a silicon elastomer, a        silicon rubber, a styrene-isoprene elastomer, a        styrene-butadiene elastomer, a styrene-ethylene/butylene-styrene        elastomer, a styrene-ethylene/propylene-styrene elastomer, an        ethylene-butadiene-styrene elastomer, a siloxane polymer, or a        poly-isocyanate.        50. The dry self-adhesive of any one of items 29 to 49, wherein        the micro-featured and nano-featured surface has a roughness        average in amplitude (R_(a)) ranging between about 0.2 μm and        about 3.0 μm, between about 0.2 μm and about 1.5 μm, between        about 0.25 μm and about 1.5 μm or between about 0.2 μm and about        0.7 μm.        51. The dry self-adhesive of any one of items 29 to 50, wherein        the micro-featured and nano-featured surface has a mean spacing        of profile irregularities (RS_(m)) between about 20 μm and about        2000 μm, between about 20 μm and about 1500 μm, between about 20        μm and about 1000 μm or between about 20 μm and about 500 μm.        52. A fastener comprising the dry adhesive according to any one        items 1-22, a surface according to any one of items 23-26 or a        dry self-adhesive according to any one of items 27-51.        53. A game or toy comprising the dry adhesive according to any        one items 1-22, a surface according to any one of items 23-26 or        a dry self-adhesive according to any one of items 57-51.        54. A board for displaying an advertisement having a compliant        surface as defined in any one items 1-26 on its backside, the        board having a micro-featured and nano-featured surface as        defined in any one of items 1-26, the compliant surface being        capable of forming upon contact a dry adhesive bond with the        micro-featured and nano-featured surface.        55. The board of item 54, wherein the micro-featured and        nano-featured surface is an aluminum surface.        56. The board of item 54 or 55, wherein the advertisement        comprises a plastic sheet with an image and/or writings on its        front and the compliant surface on its backside.        57. A board for mounting a display, the board and the display        each having a dry self-adhesive surface according to any one of        items 27-51, or the board comprising one of a compliant surface        as defined in any one items 1-26 and a micro-featured and        nano-featured surface according any one of items 1-26, and the        display comprising the other of the compliant surface and the        micro-featured and nano-featured surface.        58. A dart game comprising a target printed on a micro-featured        and nano-featured surface according to any one of items 1-26 and        one or more darts having a tip made of a compliant material and        having a compliant surface according to any one of items 1-26.        59. A shooting game comprising a micro-featured and        nano-featured surface according to any one of items 1-26        embedded in a piece of clothing and one or more projectiles        having a compliant surface according to any one of items 1-26.        60. A laminating film for laminating a micro-featured and        nano-featured surface, the laminating film having a compliant        surface having a hardness of about 60 Shore A or less, the        compliant surface being capable of forming upon contact a dry        adhesive bond with the micro-featured and nano-featured surface.        61. The laminating film of item 60, wherein the compliant        surface is a surface of a compliant layer located on a base        layer.        62. The laminating film of item 60, wherein the compliant        surface comprises spots of a compliant material deposited on a        base layer.        63. The laminating film of item 61 or 62, wherein the base layer        is a polymeric film, such as a PET film.        64. The laminating film of any one of items 60 to 63 wherein the        compliant surface has a hardness of about 55, 50, 45, 40, 35,        30, 25, 20 Shore A or less.        65. The laminating film of any one of items 60 to 64, wherein        the compliant surface comprises a polymer.        66. The laminating film of item 65, wherein the polymer        comprised in the compliant surface is a thermoplastic elastomer        or a crosslinked elastomer.        67. The laminating film of item 66, wherein the polymer        comprised in the compliant surface is a silicon elastomer, a        silicon rubber, a styrene-isoprene elastomer, a        styrene-butadiene elastomer, a styrene-ethylene/butylene-styrene        elastomer, a styrene-ethylene/propylene-styrene elastomer, an        ethylene-butadiene-styrene elastomer, a siloxane polymer, or a        poly-isocyanate.        68. The laminating film of any one of items 60 to 67, wherein        the micro-featured and nano-featured surface is a paper surface.        69. The laminating film of item 68, wherein the paper surface is        a surface of an inkjet photo paper.        70. A method of manufacturing a micro-featured and nano-featured        surface, the method comprising creating micro-features and        creating nano-features on the surface.        71. The method of item 70, wherein the micro-features are        created by mechanical graining, chemical graining, electrolytic        graining, plasma graining, by stretching a ductile material        comprising nano additives or a combination thereof.        72. The method of item 70 or 71, wherein nano-features are        created by electrolytic anodization, by incorporation of nano        porous and/or nano particulate materials or by selective        extraction of a phase in a phase separated material.        73. The method of any one of items 70 to 72, further comprising        creating functional groups on the micro-featured and        nano-featured surface.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings:

FIG. 1 is a scanning electron micrograph (SEM) of a micro-featured andnano-featured aluminum surface according to Example 1;

FIG. 2 is a scanning electron micrograph (SEM) of a micro-featured andnano-featured aluminum surface according to Example 2;

FIG. 3 is a scanning electron micrograph (SEM) of a micro-featured andnano-featured aluminum surface according to Example 3;

FIG. 4 is a scanning electron micrograph (SEM) of a micro-featured andnano-featured aluminum surface according to Example 4;

FIG. 5 is a scanning electron micrograph (SEM) of a micro-featured andnano-featured polyethylene terephthalate surface according to Example 6;

FIG. 6 is a flowchart of a process for creating micro-features andnano-features on a surface in accordance with one or more embodiments ofthe present invention;

FIG. 7 is a flowchart of a process for creating micro-features andnano-features on an aluminum surface in accordance with one or moreembodiments of the present invention;

FIG. 8 (A to C) shows dry self-adhesives according to variousembodiments of the invention;

FIG. 9 is a dry self-adhesive according to an embodiment of theinvention;

FIG. 10 is a dry self-adhesive according to another embodiment of theinvention;

FIG. 11 is a dry self-adhesive according to yet another embodiment ofthe invention;

FIG. 12 is a dry self-adhesive according to another embodiment of theinvention;

FIG. 13 shows a bi-layer laminating film according to an embodiment ofthe invention;

FIG. 14 shows a four-layer laminating film according to an embodiment ofthe invention

FIG. 15 is a photograph showing the adhesion of three donut-shapedobjects made of a compliant material on a vertically held substrate witha micro-featured and nano-featured surface according to the invention;

FIG. 16 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on the same substrate as FIG. 15,but held facedown;

FIG. 17 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on another substrate with amicro-featured and nano-featured surface according to the invention;

FIG. 18 is a photograph showing the adhesion of four donut-shaped andone thread-like objects made of a compliant material on the samesubstrate as FIG. 17, but held facedown;

FIG. 19 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on another vertically heldsubstrate with a micro-featured and nano-featured surface accordingExample 6;

FIG. 20 is a photograph showing the substrate of FIG. 19 bearing fourdonut-shaped objects can be supported by holding one of the objects;

FIG. 21 is a photograph showing one of the inventors pulling to removeone of the four donut-shaped objects from the surface of the substrateof FIGS. 19 and 20;

FIG. 22 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on another vertically heldsubstrate with a micro-featured and nano-featured surface according tothe invention.

FIG. 23 (A to F) shows the use of a dry self-adhesive sheet according toExample 8;

FIG. 24 (A to D) shows the use of a dry self-adhesive sheet according toExample 9;

FIG. 25 (A to E) shows the use of a dry self-adhesive sheet according toExample 10;

FIG. 26 (A to D) shows the use of a dart board and darts according to anembodiment of the invention; and

FIG. 27 (A to C) shows the use of a dart board and darts according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail with reference toembodiments thereof as illustrated in the accompanying drawings. In thefollowing description, numerous specific details are set forth in orderto provide a thorough understanding of the present invention. It will beapparent, however, to one skilled in the art, that the present inventionmay be practiced without some or all of these specific details. In otherinstances, well known process steps and/or structures have not beendescribed in detail in order to not unnecessarily obscure the presentinvention.

In accordance with the present invention, there is provided a dryadhesive comprising a micro-featured and nano-featured surface (alsocalled hereinafter the “featured surface”), and a compliant surfacehaving a hardness of 60 Shore A or less; the featured surface and thecompliant surface forming upon contact a dry adhesive bond with eachother.

In an embodiment, the present invention relates to micro-featured andnano-featured surfaces for the dry adhesion of a compliant surfacehaving a hardness of 60 Shore A or less. These featured surfaces areable to form upon contact a dry adhesive bond with the compliantsurface. The present invention also relates to methods for producingsuch featured surfaces. The present invention also relate to the use ofa micro-featured and nano-featured surface as a substrate for the dryadhesion a compliant surface

In another embodiment, the present invention relates to dryself-adhesive based on the dry adhesive of the invention. In these dryself-adhesives, the featured surface and the compliant surface are eachlocated on one or more different areas of a same physical surface. Thedry self-adhesive thus comprises a surface having one or moremicro-featured and nano-featured areas (also called hereinafter the“featured areas”) and one or more compliant areas, wherein the compliantareas have a hardness of 60 Shore A or less. In the dry self-adhesive,the featured areas are able to form upon contact a dry adhesive bondwith the compliant areas.

In yet another embodiment, there is also provided a laminating filmbased on the dry adhesive of the invention. The laminating filmcomprises a compliant surface having a hardness of 60 Shore A or lessfor laminating a micro-featured and nano-featured surface. Thiscompliant surface is capable of forming upon contact a dry adhesive bondwith the featured surface to be laminated.

In other embodiments, the present invention relates to variousapplications of the above.

It is to be noted that herein, phrasings like “micro-featured andnano-featured surface” and “compliant surface” do not necessarilyindicate that a whole surface is micro-featured and nano-featured orcompliant. Rather, as will be seen below, only one large or severalsmall areas of the surface can be micro-featured and nano-featured orcompliant. This is the case notably for the dry self-adhesive, but alsothe dry-adhesive, the micro-featured and nano-featured surfaces for thedry adhesion and the laminating films. Herein, unless otherwiseindicated, “micro-featured and nano-featured surface” (or “featuredsurface”) and “compliant surface” designate surfaces that are completelyor only partially micro-featured and nano-featured or compliant,respectively.

It is also to be noted that the micro-featured and nano-featured surfaceand the compliant surface may be simply supported on a substrate, thiswould be the case of inkjet photo paper or of an aluminum sheet modifiedto bear micro-features and nano-features (see below for more details),or they can be a surface of an object, for example the compliant surfacemay be a surface of an object made of a compliant material.

Herein, “dry adhesion” is an adhesion where no conventional adhesive isused. No glue, epoxy or other tacky material is used. Without beingbound by theory, it is believed that the compliant material adheres tothe micro-featured and nano-featured surface because of physical (e.g.van der Waals) and/or chemical interactions between the micro-featuresand the nano-features and the compliant surface, which, being compliant,conforms with the topography of the featured surface to form reversiblemechanical interlock. Thus, when the compliant surface is brought intophysical contact with the featured surface, an adhesive bondinstantaneously forms between them. This bond is reversible and thesurfaces may be detached from one another.

In embodiments, the detachment is non-destructive and/or residue-free.This can be the case, for example, when the featured surface is made ofa durable material that does not generate any particle and when the tearstrength of the compliant surface is sufficiently high so that it doesnot leave any residue behind. In these embodiments, the attachment anddetachment process is fully reversible and non-destructive and can thusbe repeated a large number of times.

In other embodiments, the detachment is not completely non-destructiveand/or residue-free. This can be the case when the featured surface isan inkjet photo paper bearing one or more fragile coatings. In suchcases, it has been observed by the inventors that detachment may causesome of the fragile coating to peel off. With repeated attachments anddetachments, the coating becomes damaged and the strength of theadhesion decreases. Therefore, the attachment and detachment process isnot fully reversible and is somewhat destructive. The attachment anddetachment can nevertheless be repeated, but not a very large number oftimes. Such embodiments are nevertheless useful in application wherebeing able to attach and detach the surface from one another a largenumber of times is not desired. This is the case when the compliantsurface is used as a laminating film for laminating a featured surface.

Words and images can be written or drawn using for example a marker, orthey can be inkjet printed on several embodiments of the micro-featuredand nano-featured surface, the compliant surface and the dryself-adhesive surface.

As a general rule, the thicker the compliant surface, the stronger thedry adhesion will be. Also, the lower the Shore A of the compliantmaterial, the stronger the dry adhesion will be.

Compliant Surface

Herein, a “compliant” surface or material is a surface or material witha relatively low modulus so that it is able to deform and conform. Inembodiments, the compliant material or surface has a hardness of 60Shore-A or less, preferably 55, 50, 45, 40, 35, 30, or 25 Shore-A orless. In these or other embodiments, the compliant material or surfacehas a hardness of 20, 25, 30, 35, 40, 45, 50, or 55 Shore-A or more

In embodiments, the compliant surface is made of an organic and/orinorganic material. Non-limiting examples of such materials includepolymers, such as thermoplastic polymers, thermoplastic elastomers, andcrosslinked elastomers. Suitable polymers include, but are not limitedto, natural polyisoprene, synthethic polyisoprene, polybutadiene,polychloroprene, butyl rubber, styrene-butadiene rubber, nitrile rubber,ethylene propylene rubber, epichlorohydrin rubber, polyacrylic rubber,silicone rubber, fluorosilicone rubber, fluoroelastomers,perfluoroelastomers, polyether block amides, chlorosulfonatedpolyethylene, ethylene-vinyl acetate, silicone elastomer, polyurethaneelastomer, aminopropyl terminated siloxane dimethyl polymers,styrene-ethylene/propylene-styrene (SEPS) thermoplastic elastomer,styrene-ethylene/butylene-styrene (SEBS) thermoplastic elastomer,styrene-isoprene-styrene (SIS) thermoplastic elastomer,styrene-butadiene-styrene (SBS) thermoplastic elastomer, and/orstyrene-ethylene/butylene-styrene grafted with maleic anhydridethermoplastic elastomer.

Table I shows non-limiting examples of thermoplastic elastomers togetherwith some of their physical properties. The thermoplastic elastomers arelisted with their hardness (Shore A), elongation at break (%), and/ortensile strength (psi). Kraton thermoplastic elastomers are availablethrough Kraton Polymers in Houston, Tex. The datasheets of thesepolymers are available to the skilled person through the websitewww.kraton.com and are hereby incorporated by reference.

TABLE I Hardness Elongation Tensile (Shore at break strength Name A) (%)(psi) KRATON ® D SIS - Styrenic block copolymers based on styrene andisoprene KRATON ® D1114 P Polymer 42 1300 4600 (Clear, liner triblockcopolymer based on styrene and isoprene with a polystyrene contact of19%.) KRATON ® D1160 B Polymer 48 1300 4640 (Clear linear triblockcopolymer based on styrene and isoprene with bound styrene of 18.5%mass.) KRATON ® D1161 B Polymer 30 1300 4060 (Clear, linear blockcopolymer based on styrene and isoprene with a polystyrene content of15%.) KRATON ® D1163 P Polymer 25 1400 1500 (Clear, linear triblockcopolymer based on styrene and isoprene, with a polystyrene content of15%) KRATON ® D SBS - Block copolymers composed of blocks of styrene andbutadiene KRATON ® D4141 K Polymer 50 1300 2750 (31% styrene) KRATON ®D4150 K Polymer 45 1400 2800 (Linear triblock copolymer based on styreneand butadiene with a polystyrene content of 31%.) KRATON ® D4158 KPolymer 41 1110 1330 (Oiled, radial copolymer based on styrene andbutadiene with a polystyrene content of 31%.) KRATON ® G SEBS/SEPS -Styrenic block copolymers with a hydrogenated midblock of styrene-ethylene/butylene- styrene (SEBS) or styrene-ethylene/propylene-styrene(SEPS) KRATON ® G1645 M Polymer 35 600 1500 (Linear triblock copolymerbased on styrene and ethylene/butylene) KRATON ® G1657 M Polymer 47 7503400 (Clear, linear triblock copolymer based on styrene andethylene/butylene with a polystyrene content of 13%) KRATON ® G1702 HPolymer 41 <100 300 (Clear, linear diblock copolymer based on styreneand ethylene/propylene with a polystyrene content of 28%. KRATON ® G4609H Polymer 22 — 800 (White mineral oil extended linear triblock copolymerbased on styrene and ethylene/butylene with a polystyrene content of33%. Nominal oil content of the polymer is 45.5% w (90 parts/100 partsrubber (phr)). KRATON ® FG - SEBS polymers with 1.0 to 1.7 wt. % maleicanhydride (MA) grafted onto the rubber midblock KRATON ® FG1924 GPolymer 49 750 3400 (Clear, linear triblock copolymer based on styreneand ethylene/butylene with a polystyrene content of 13%.)

Table II shows non-limiting examples of crosslinked elastomers togetherwith some of their physical properties. The crosslinked elastomers arelisted with their hardness (Shore A), elongation at break (%), tensilestrength (psi), and tear strength (kN/m). The silicone elastomers areavailable through Dow Corning. The datasheets of these polymers areavailable to the skilled person through the website www.dowcorning.comand are hereby incorporated by reference.

TABLE II Tensile Tear Durometer Elongation strength strength Name (ShoreA) (%) (psi) (kN/m) Dow Corning ® 3631 19 800 725 16 (Two-part, solventfree, heat-cured liquid silicone rubber.) Dow Corning ® D94-20P 21 900765 N/A (Two-part, 1:1 ratio, addition cure silicone elastomer) DowCorning ® D94-30P 33 800 1000 16.1 (Two-part, 1:1 ratio, addition curesilicone elastomer) Silastic ® LC-20-2004 20 900 940 24 (20 Durometer, 2parts, 1 to 1 mix, translucent, FDA 21 CFR 177.2600 and BfR, XV, moldingand injection molding grade Liquid Silicone Rubber) Silastic ® LC-942620 790 609 23 (Two-part liquid silicone rubber) Silastic ® 94-595 42 6101450 34 (40 Durometer, 2-part, 1 to 1 mix, translucent Liquid SiliconeRubber) Silastic ® 94-599 49 590 1595 32 (47 Durometer, 2-part, 1 to 1mix, translucent, molding grade, Liquid Silicone Rubber) Silastic ®LC-9434 33 790 797 32 (two-part liquid silicone rubber) Silastic ®LC-9436 29 720 855 28 (two-part liquid silicone rubber) Silastic ®LC-9451 50 540 1102 30 (two-part liquid silicone rubber) Silastic ®LC-9452 50 560 1015 34 (two-part liquid silicone rubber) Silastic ®LC-9454 50 530 1044 29 (two-part liquid silicone rubber) DOW CORNINGClass VI Elastomers C6-530 30 831 1189 27.5 (heat cured elastomer rawmaterials) DOW CORNING Class VI Elastomers C6-540 40 742 1293 41.9 (heatcured elastomer raw materials) Dow Corning ® S40 40 864 1250 31.2(Two-part platinum-catalyzed silicone elastomer) Dow Corning ® S50 48610 1275 42.5 (Two-part platinumcatalyzed silicone elastomers) DowCorning ® D94-45M 45 600 1050 45 (Two-part, 1:1 ratio, addition curesilicone elastomer)

Another example of compliant material is QLE1031, heat curable siliconeelastomer available from Quantum Silicones, Va., USA. The datasheets ofthese polymers are available to the skilled person through the websitewww.quantumsilicones.com and are hereby incorporated by reference.

In embodiments, inorganic materials, such as single-crystal siliconfabricated as flexible nano membranes, are used as the compliantmaterial. Inorganic nano membranes may indeed conform to themicro-features and nano-features of the featured surface to produce aninstantaneous, reversible dry adhesion.

The compliant surface can be the surface of an object made of acompliant material. This object may be a film or any three-dimensionalobject. In other embodiments, the compliant surface is a surface of acompliant layer supported on a substrate, for example a plastic sheet orthe like.

In these and other embodiments, the compliant surface is thin enough tobe flexible. As such, it can be provided in various forms and shape. Ina particular embodiment, the compliant surface is provided in the formof a roll.

In these and other embodiments, the compliant surface is provided with aconventional adhesive backing (which may be protected by a peel-off filmuntil it is used) for adhering the compliant surface to a substrate.

Micro-Featured and Nano-Featured Surface

Herein, a “micro-featured and nano-featured” (or “featured”) surface isa surface that bears micro-features and nano-features. It has beenobserved by the inventors, as shown in Comparative Example 1, that thepresence of both micro-features and nano-features produces a strong dryadhesive bond. Such micro-features and nano-features can be seen inFIGS. 1 to 5. In particular, the micro-features and nano-features can bemicropores and nanopores of different regular or irregular shapes.

Herein, “nano”, as in nano-features and nanopores, refers to featuresand pore with sizes in the range of about 1 to about 100 nanometers (nm)and “micro”, as in micro-features and micropores, refers to features andpores with sizes greater than about 0.1 up to about 5 microns (μm).

The roughness of the micro-featured and nano-featured surface (or areas)can be expressed using R_(a), the roughness average in amplitude, andRS_(m), the mean spacing of profile irregularities. As will be seenbelow, the density, micro-features, nano-features, and surfacefunctionalization of the micro-featured and nano-featured surface can becontrolled and tailored as described below.

In embodiments, R_(a) varies from about 0.2 μm to about 3.0 μm. In morespecific embodiments, it varies between about 0.2 μm and about 1.5 μm orpreferably between about 0.25 μm and about 1.0 μm or between about 0.2μm and about 0.7 μm. In these or other embodiments, RS_(m) may vary fromabout 20 nm to about 2,000 nm. In more specific embodiments, it variesbetween about 20 nm and about 1500 nm, or between about 20 nm and about1,000 nm or between about 20 nm and about 500 nm.

In embodiments, the featured surface is a metallic surface, a glasssurface, a paper surface or a polymeric surface. Non-limiting examplesof metallic surfaces include aluminum, copper, and stainless steelsurfaces modified to bear micro-features and nano-features. Non-limitingexamples of polymeric surfaces include polyethylene terephthalate,polyolefin, polyamine, polysiloxane, polyimide and polyurethanesurfaces, each of which optionally comprising inorganic or organicparticles. In these and other embodiments, the particles are used toimpart micro-features and/or nano-features to the surface. Inembodiments, the organic and inorganic particles are nanoparticlesand/or microparticles comprising nanopores. In embodiments, nanoporousand/or nanoparticulate materials such as calcium carbonate, zeolites,fumed silica, zirconium oxide, titanium oxide, activated carbons,polyhedral oligomeric silsesquioxanes (POSS), carbon nanotubes,graphene, alumina (such as Cab-O-Sperse PG008) and/or activated aluminaare used.

In embodiments, the featured surface is paper-based. Not all types ofpaper have a micro-featured and nano-featured surface. However, manycommercially available papers do have such a surface. This is the casenotably of many papers for printing with inkjet printers, especially forprinting photos with such printers (hereinafter “inkjet photo paper”. Inembodiments, the featured surface is a surface of a microporous inkjetpaper or a resin coated inkjet paper. There is a plurality of suchinkjet papers available under different brands. These papers havemicro-features and nano-features that allow faster drying of aqueous inkand better overall quality of the printed photo. Depending on theirmethod of manufacture, these papers will bear one or more coatings withor without organic and inorganic particles. These coatings and/orparticles provide the micro-features and nano-features. In embodiments,these inkjet papers comprise fumed silica and/or fumed alumina, whichmay be held together by polyvinyl alcohol. Such inkjet papers are widelyavailable from Epson™, Canon™, HP™, Kodak™, and/or Ilford™. These photopapers may be available in various finishes such as glossy, matte,silky, and lustre. Non-limiting examples of suitable inkjet photo paperinclude:

Epson™ Ultra Premium Photo Paper Glossy,

Epson™ Premium Resin Coated Glossy Photo Paper,

Canon™ Matte Photo Paper,

Canon™ Photo Paper Plus II Glossy,

HP™ Advanced Photo Paper Glossy,

Kodak™ Photo Paper Glossy,

Kodak™ Photo Paper Matte,

Ilford™ Galerie Smooth Pearl Paper, and

Ilford™ Galerie Smooth Gloss Paper.

In embodiment, the surface is an aluminum surface. Such surface can beproduced with a thickness down to 6 μm, which makes them flexible.

In embodiment, the surface is a polyethylene phthalate surfacecomprising one or more nanoporous and/or nanoparticulate materials.

In several embodiments, the micro-featured and nano-featured surface isthin enough to be flexible. As such, it can be provided in various formsand shape. In a particular embodiment, the featured surface is providedin the form of a roll.

In a more specific embodiment, the micro-featured and nano-featuredsurface is adhered to the compliant surface and both surfaces are thenrolled. Thus, the dry adhesive itself is provided as a roll.

In these and other embodiments, the featured surface and/or thecompliant surface can be provided with a conventional adhesive backing(which may be protected by peel-off films until they are used) foradhering them to substrates. This allows adhering the compliant surfaceto a first substrate and the micro-featured and nano-featured surface toa second substrate and reversibly adhering the first substrate to thesecond substrate via the dry adhesive featured surface/compliant surfaceinteraction.

The micro-featured and nano-featured surface allows the instantaneousdry adhesion of the compliant surface. This is unexpected because thefeatured surface and the compliant surface, have no adhesive property oftheir own; i.e. they are non-tacky.

Method for Producing a Micro-Featured and Nano-Featured Surface

As stated above, the micro-featured and nano-featured surface can be acommercially available product such as inkjet photo paper. This surfacecan also be produced by modifying a surface of a material to createmicro-features and nano-features thereon.

Thus, turning now to a method of making micro-featured and nano-featuredsurfaces, FIG. 6 shows a flowchart of a process for creatingmicro-features and nano-features on a surface in accordance with anembodiment of the invention. This flow chart illustrates a top levelprocess 100 for creating surfaces of e.g. metal, plastic and/or glasswith micro-features and nano-features. In this process, steps 102, 104,110, 112, and 114 are optional.

As shown in FIG. 6, process 100 may starts with optional step 102, inwhich an operator selects, if needed, the material to be processed.

In optional step 104, the selected material is treated to prepare thesurface of the selected material as needed.

Consider the situation where for example, the selected material is metalor glass. The selected material may be pre-treated to clean it so as toremove accumulated surface contaminants such as particulates and/or oilsand greases. This cleaning may comprise of a single rinse with deionizedwater or a plurality of sub-steps. For example, it may comprise, but isnot limited to, one or more of rinsing with deionized water, degreasingwith a neutral, acidic and/or alkaline detergent solution, rinsing withdeionized water, and drying. A person of ordinary skills in the artwould appreciate that pre-treatment step 104 may be modified to achievethe desired level of cleanliness depending on the selected material andthe level and nature of the contamination on the surface of the selectedmaterial.

Consider another situation wherein for example, the selected material isa raw polymer in pellets form. In such a case, the raw polymer may becompounded, in pre-treatment step 104, with other additives in effectiveconcentration to attain desired end user properties. To simplifydiscussion, these additives are not discussed in details since additivessuch as plasticizers, fillers, colorants, processing aids, antioxidants,and flame retardants are well known to persons of ordinary skills in theart, who will appreciate that they may be selected depending on end useapplication.

In an embodiment, nanoporous and/or nanoparticulate materials, such ascalcium carbonate, zeolites, fumed silica, zirconium oxide, titaniumoxide, activated carbons, polyhedral oligomeric silsesquioxanes (POSS),carbon nanotubes, graphene, and/or activated alumina, are employed asadditives in pre-treatment step 104. The nano additives are compoundedwith the aforementioned raw polymer to form a composition for subsequentprocessing steps.

As shown in FIG. 6, step 106 entails the creation micro-features on thesurface of the selected material. Non-limiting examples of treatmentsallowing the creation of micro-features on the surface includemechanical graining, chemical graining, electrolytic graining, plasmagraining and combination thereof.

In embodiments, mechanical graining is performed on the surface of theselected material by mechanical abrasion, such as scrubbing and/orsandblasting. Graining with sand and/or pumice can be performed usingwire brushes or marbles on the surface of the selected material. Theresulting grained surface may be relatively rough. In other embodiments,the surface of the selected material is roughened by blasting, underhigh pressure, a stream of abrasive materials.

In embodiments, chemical graining is performed on the surface of theselected material through chemical etching or milling by exposing thesurface of the selected material to a caustic solution (such as a sodiumhydroxide solution) and/or an acidic solution (such as a hydrochloricacid solution). For example, glass may be chemically grained by exposingthe glass surface to a sodium fluoride cream.

In an embodiment, electrolytic graining is performed on the surface ofthe selected material, for example a metal such as aluminum, by exposingthe surface of the selected material to the action of an electricalcurrent in an aqueous electrolytic solution. The grained surfaceresulting from electrolytic graining may be very fine and uniform.

In another embodiment, plasma graining may be performed by exposing thesurface of the selected material to low temperature, radio frequency(RF) plasma in vacuum. For example, the plasma chamber may be evacuatedto about 10⁻³ to about 10⁻⁶ torr and the RF plasma is powered in therange from about 500 kiloHertz to about 10 megaHertz.

Alternatively, other method(s) may be employed to create micro-featureson the surface of the selected material. Consider the situation whereinfor example, the selected material is a ductile material such aspolypropylene. In such cases, nano additives may be selectively added inpre-treatment step 104 for compounding. In accordance with an embodimentof the invention, the polypropylene film may then be uniaxially orbiaxially stretched to induce cavitation around the nano additives andthus create micropores.

As may be appreciated from the foregoing, a plurality of methods may beemployed to selectively create micro-features on the surface of theselected material. A person of ordinary skills in the art willappreciate that micro-feature creation step 106 may be modified toachieve the desired microtopography.

Step 108 of FIG. 6 entails creating nano-features on the surface of theselected substrate of step 102. In a non-limiting example, nano-featureson a surface of the selected material are created by electrolyticanodization and/or by incorporating nano porous and/or nano particulatematerials in the material.

In an embodiment, electrolytic anodization may be performed on thesurface of the selected material, such as a metal. Consider thesituation where the selected material is aluminum. Anodization is anelectrochemical process wherein the surface of the selected material,aluminum, is exposed to the action of an electrical current in anaqueous acidic electrolytic solution, such as, for example, dilutedsulfuric acid. The surface resulting from sulfuric acid anodization willhave a porous aluminum oxide layer. The idealized porous aluminum oxidelayer may be represented by a cellular structure with a central pore ineach cell. The aluminum oxide film thickness, the cell size and the poresize will depend on the process conditions such as the composition ofthe aqueous acidic electrolytic solution, the temperature, and/or thecurrent density. The aluminum oxide layer from electrolytic anodizationmay produce surfaces with high densities of nanopores. The cells mayhave diameter in the range of about 50 to about 300 nm. The pores mayhave diameter in the range of about 15 to about 150 nm. The cell densitymay range from about 10 to 100 cells per μm².

Consider the situation where the selected material is glass. This glassmay be, for example, the extraction product of phase separated sodiumboron silicate glass. In an embodiment, phase separated sodium boronsilicate glass may be made porous with pore sizes in the range of about1 to about 500 nm.

Alternatively other method(s) may be employed to create nano-features onthe surface of the selected material. Consider the situation where forexample, the selected material is a polymeric material such as apolyethylene, polypropylene, polyamide, polyimide or polyethyleneterephthalate film. In an embodiment, nano and micro particulateadditives may be selectively added in pre-treatment step 104 forcompounding. In accordance with an embodiment of the invention, theparticulate additive may be fumed silica oxide. Fumed silica oxidetypically may have particle size ranging from about 5 to about 2,000 nmwith a surface ranging from about 50 to about 600 m²/g.

As may be appreciated from the foregoing, a plurality of methods can beemployed to selectively create nano-features on the surface of theselected material. A person of ordinary skills in the art wouldappreciate that nano-feature creation step 108 may be modified toachieve the desired nanotopography.

Step 110 of FIG. 6 is optional and entails the creation of functionalgroup(s) on the surface of the selected substrate. In a non-limitingexample, functionalization on a surface of the selected material may becreated by employing different functional chemical agents. Non-limitingexamples of such functional groups include phosphate fluoride (obtainedfor example by treating aluminum after anodization with a solution ofNaH₂PO₄ and NaF). Other treatments include treatment with polyvinylphosphoric acid and/or vinyl phosphoric acid-methacrylic acid as well astreatments with aqueous solutions containing sodium silicate.

Post treatment step 112 of FIG. 6 may optionally be carried out inprocess 100 to perform various treatments. In a non-limiting example,the surface of the selected material may be cleaned, rinsed,neutralized, colored, sealed, and/or cut to achieve end userrequirements.

As shown in FIG. 6, process 100 is terminated at step 114. The treatedsurface of the selected material is ready for use.

Aluminum is an advantageous raw material due some of its characteristicsincluding lightness, specific strength, machinability, and surfacetreatability. FIG. 7 shows a flowchart of process 200 for creatingmicro-features and nano-features on an aluminum surface in accordancewith one or more embodiments of the present invention. To facilitateunderstanding, FIG. 7 will be discussed in relation to FIG. 6 toillustrate how the steps in FIG. 7 may be applied to the aluminumsurface. In this figure, steps 202, 204, 212, 214 and 216 are optional.Additionally, either or both of steps 206 and 208 can be carried out inprocess 200.

In accordance with an embodiment of this invention, surface treatmentprocess 200 for aluminum may be performed on a continuous productionline with a speed of, for example, about 10 meters per minute. Inaccordance with another embodiment of the invention, the surfacetreatment process 200 is a batch process.

As shown in FIG. 7, process 200 starts with optional step 202, in whichan operator selects aluminum for processing.

In accordance with one or more embodiments, the aluminum surface of step202 may be pre-treated in optional step 204 of FIG. 7.

In pre-treatment step 204, the aluminum surface may be, for example,cleaned. Step 204 of FIG. 7 corresponds to pre-treatment step 104 ofFIG. 6. In an embodiment, the aluminum surface may be cleaned bydegreasing. Degreasing may include washing the aluminum surface with analkaline solution containing an effective concentration of causticsolution to remove oils and greases. In a non-limiting example, theeffective concentration of the caustic solution may be about 3.85 g/L ofsodium hydroxide (NaOH) and/or about 0.95 g/L of sodium gluconate. Anon-limiting example of the process conditions for degreasing is washingthe aluminum surface in the caustic solution at about 70° C. for about 3minutes. In an embodiment, degreasing may further include neutralizingthe degreased aluminum surface with an effective acidic solution. In anon-limiting example, the effective concentration of the acidic solutionmay be about 0.5 g/L of hydrochloric acid (HCl). The neutralizedaluminum surface may further be rinsed with de-ionized water. A personof ordinary skills in the art would appreciate that step 204 may bemodified to achieve the desired level of cleanliness depending on theselected material and the contaminants on the aluminum surface.

In accordance with an embodiment, one or both of mechanical grainingstep 206 and electrolytic graining step 208 are employed in process 200to create micro-features on the surface of the aluminum. Both of step206 and step 208 of FIG. 7 correspond to step 106 of FIG. 6.

In an embodiment, micro-features may be created on the aluminum surfaceby mechanical graining step 206. In a non-limiting example, mechanicalgraining step 206 may be performed by employing nylon brush rollers onthe aluminum surface in an aqueous suspension containing about 400 meshpumice stone powder. The mechanically grained aluminum surface may thenbe washed with de-ionized water.

Additionally or alternatively, micro-features may be created on thealuminum surface by electrolytic graining step 208. In a non-limitingexample, electrolytic graining step 208 may be performed by employingcarbon electrodes and different effective acidic electrolyte solutionsat about 25° C. with different effective alternating current density. Innon-limiting examples, effective acidic electrolyte solutions maycomprise at least one of about 6.0 g/L hydrochloric acid solution, about8.0 g/L hydrochloric acid and about 16.0 g/L acetic acid (CH₃COOH)solution, and/or about 10 g/L nitric acid (HNO₃) solution. In anexample, the effective alternating current density may range from about160 to about 1250 C/dm².

In an embodiment, electrolytic graining step 208 further includesneutralizing the electrolytically grained surface with an effectiveaqueous alkaline solution. In a non-limiting example, the effectiveconcentration of the aqueous alkaline solution may be about 3.0 g/L ofsodium hydroxide. The neutralized aluminum surface may then be rinsedwith de-ionized water. A person of ordinary skills in the art wouldappreciate that the conditions used in the mechanical graining step 206and electrolytic graining step 208 may be modified to achieve thedesired level of micro-features depending on the end user applicationrequirements. Also, the order of these graining operations can bereversed.

As shown in FIG. 7, the next step is electrolytic anodization step 210,which entails the creation of nano-features on the surface of thealuminum. Step 210 of FIG. 7 corresponds to step 108 of FIG. 6.Nano-features are created on the aluminum surface by electrolyticanodization, which form an aluminum oxide layer having a nano porousstructure and harden the surface of the grained aluminum. In anon-limiting example, electrolytic anodization step 210 may be performedusing 316 stainless steel electrodes and different effective acidicelectrolyte solutions at about 20° C. with different effective directcurrent density. In embodiments, the effective acidic electrolytesolutions may be at least one of about 140.0 g/L sulfuric acid (H₂SO₄)solution and/or about 160 g/L phosphoric acid (H₃PO₄) solution. In anexample, the effective direct current density ranges from about 5.6 to 7A/dm². In an embodiment, electrolytic anodization step 210 of FIG. 7 mayfurther include rinsing the electrolytically anodized aluminum surfacewith de-ionized water. A person of ordinary skills in the art wouldappreciate that the conditions used for the electrolytic anodization maybe modified to achieve the desired nanotopography.

As shown in FIG. 7 in accordance with an embodiment, surfacefunctionalization step 212 may be optionally carried out to createfunctional groups on the surface of the aluminum. Step 212 of FIG. 7corresponds to surface functionalization creation step 110 of FIG. 6.

In an embodiment, the functionalization of the aluminum surface insurface functionalization step 212 is carried out to enhanceintermolecular interactions and improve adhesion to the surface. In anon-limiting example, surface functionalization may be performed byimmersing the aluminum surface into an effective aqueous solutioncontaining a plurality of surface functionalized chemical agents atabout 60° C. In non-limiting examples, effective aqueous solutionscontaining functionalized chemical agents may comprise at least one ofabout 50.0 g/L monosodium phosphate (NaH₂PO₄) and/or about 0.80 g/Lsodium fluoride (NaF) solution and/or about 0.30 g/L vinyl phosphoricand acrylic copolymer solution. In an embodiment, surfacefunctionalization step 212 may further include rinsing thefunctionalized aluminum surface with de-ionized water and/or drying thefunctionalized aluminum surface at about 120° C. with hot air. A personof ordinary skills in the art would appreciate that the optional surfacefunctionalization step 212 may be modified to achieve the desiredsurface functionalities.

Optional post treatment step 214 of FIG. 7 comprises various treatmentsof the aluminum substrate. In embodiments, the surface may be cleaned,rinsed, neutralized, colored, sealed, and/or cut to achieve end userrequirements.

In a specific embodiment, the surface of the treated aluminum may becolored by immersing it in a dye solution before sealing it to create acolored surface. For example, the treated surface may be colored redwith a about 2.0 g/L to about 10 g/L dye solution with pH of about 4 toabout 6 for about 1 to about 30 minutes at temperature between about 140and about 160° F. The dye may be e.g. a metal-free azo dye such asOrcoAluminum™ Red CW.

A person of ordinary skills in the art would appreciate that the posttreatment step 214 may be modified to achieve desired surfacecharacteristics.

As shown in FIG. 7, process 200 may be terminated at step 216. Thetreated aluminum surface is ready for use.

A person of ordinary skills in the art would appreciate that the process200 of FIG. 7, in particular, and the process 100 of FIG. 6, in general,may be modified to achieve the desired surface characteristics of aplurality of materials.

As can be appreciated from the foregoing, selected materials are treatedto create micro-features and nano-features and optional surfacefunctionalities, which result in micro-featured and nano-featuredsurfaces that act as dry adhesive for non-tacky, dry compliant surfaces.Advantageously, the above treatment processes may be employed on popularraw material, such as aluminum, to allow unexpected adhesion to commonlyavailable elastomer, in contrast with current attempts to create dryadhesives. Thus, the adhesion of the treated surface (made of commonlyavailable raw materials) to widely available compliant materials enablesmass implementation of the invention.

Dry Self-Adhesive

In a particular embodiment of the above dry adhesive, the featuredsurface and the compliant surface having a hardness of 60 Shore A orless are each located on one or more different areas of a same physicalsurface. It this case, the micro-featured and nano-featured area(s)is(are) capable of forming upon contact a dry adhesive bond with thecompliant area(s) and the dry adhesive is thus self-adhesive.

Therefore, the present invention also provides a dry self-adhesive. Thisdry self-adhesive comprises a surface bearing one or more micro-featuredand nano-featured areas and one or more compliant areas, which will bereferred hereinafter as a dry self-adhesive surface. This dryself-adhesive surface can adhere to itself or other surfaces like itselfsimply by bringing the compliant area(s) into physical contact with thefeatured area(s). The surface bearing these areas is thus a dryself-adhesive in the sense it that it can adhere to itself and/or toother self-adhesive surfaces like itself through a dry adhesive bond(without using any conventional adhesive).

Depending on the intended use of the dry self-adhesive, the featuredareas and the compliant areas can be as small as 1 μm or as large asseveral centimeters. Therefore, in embodiments, the featured areasand/or the compliant areas are, for example, several hundreds μm or afew mm in size. For a narrow strip of tape, the areas may be quite smalland have, for example, a diameter as small as 1 micrometer.Alternatively, for a large construction block toy, e.g. a Lego™ block,the areas may have a diameter of several centimeters.

The dry self-adhesive can adhere to itself when it is bent so that thecompliant area(s) are brought into physical contact with themicro-featured and nano-featured area(s). In embodiments where the dryself-adhesive cannot be bent, it is cut so that at least part of themicro-featured and nano-featured area(s) and part of the compliantarea(s) are separated from each other. The cut parts are then placedface-to-face so that the compliant area(s) are brought into physicalcontact with the micro-featured and nano-featured area(s).

In several embodiments, the dry self-adhesive is thin enough to beflexible. As such, it can be provided in various forms and shape. In aparticular embodiment, the dry self-adhesive surface is provided in theform of a roll.

In these and other embodiments, the dry self-adhesive is provided with aconventional adhesive backing (which may be protected by a peel-off filmuntil it is used) for adhering the dry self-adhesive to one or moresubstrates. This allows reversibly adhering these various substrates toeach other via the interaction of the dry self-adhesive with itself.

FIG. 8 (A to F) shows dry self-adhesives according to various embodimentof the invention. In one embodiment shown in FIG. 8A, the surfacecomprises several micro-featured and nano-featured areas (hatchedsquares) and several compliant areas (dotted squares). In anotherembodiment shown in FIG. 8B, the micro-featured and nano-featured areasand the compliant areas are separated from each other rather than beingcontiguous. In FIG. 8C, the shape of the micro-featured andnano-featured areas is different from that of the compliant areas. Itshould be noted that the micro-featured and nano-featured areas and thecompliant areas can be of regular or irregular shape. In FIG. 8D, themicro-featured and nano-featured areas and the compliant areas areirregularly arranged. It will be clear to the skilled person that themicro-featured and nano-featured areas and compliant areas can berandomly or regularly distributed throughout the surface. Also, thenumber of micro-featured and nano-featured areas is different from thenumber of compliant areas. In FIG. 8E, the dry self-adhesive surfacecomprises only one micro-featured and nano-featured area (hatchedrectangle) and one compliant area (dotted rectangle). This dry adhesivesurface can be, for example, cut as shown in FIGS. 8F and 8G so that atleast part of the micro-featured and nano-featured area and part of thecompliant area are separated from each other.

FIG. 9 shows an embodiment of the dry self-adhesive. In this figure,compliant areas 304 are spread on a micro-featured and nano-featuredsurface 302 (for example, the modified surface of an aluminum sheet).Note that it is also possible to have micro-featured and nano-featuredareas 304 spread on a compliance surface 302.

FIG. 10 shows another embodiment of the dry self-adhesive. In thisFigure, compliant areas 304 are spread on micro-featured andnano-featured surface 302 of a paper sheet 306 backed by a plastic layer308.

FIG. 11 shows another embodiment of the dry self-adhesive. Thisembodiment is similar to the embodiment shown in FIG. 10, except that aregular (tacky) adhesive layer 310 covers the plastic layer 308 and thata peel-off layer 312 covers the adhesive layer 310. In use, thisparticular embodiment of the invention can be permanently adhered to asurface by peeling off the peal-off layer 312 and putting the adhesivelayer 310 in contact with the surface. The compliant areas 304 and themicro-featured and nano-featured surface 302 then allow adhesion ofother surfaces with compliant area(s) and/or micro-featured andnano-featured area(s).

FIG. 12 shows another embodiment of the dry self-adhesive. In thisembodiment, a surface 316 bears compliant areas 304 and micro-featuredand nano-featured areas 314. The surface 316 may be for example aplastic or paper sheet.

In embodiments in which the featured areas and the compliant areas arealternating, such as for example when they are arranged in a check-boardpattern, and in which one type of area is raised compared to the othertype of area (see for example FIG. 9), the size of the raised areas ispreferably somewhat smaller than the spacing in between them so as toallow the raised areas to better fit into the spacing. This allowsbetter physical contact between both type or areas and thus the desireddry adhesion. A way of describing these dry self adhesives is to definean “area ratio”, which is the ratio of the total area occupied by theraised areas to the total area occupied by the areas of the other type.In embodiments, this area ratio is 1:1.1 or more.

As is apparent from the above, the dry self-adhesive can be produced byprinting or coating a compliant material onto a micro-featured andnano-featured substrate so as to form compliant area(s) or by printingor coating a micro-featured and nano-featured material onto a compliantsubstrate so as to form micro-featured and nano-featured area(s). Inanother embodiment, both micro-featured and nano-featured area(s) andcompliant area(s) can be printed on coated on a substrate, such as forexample, a plastic, paper or metal sheet.

Laminating Films

The present invention also relates of laminating films featuring the dryadhesive. More specifically, the present invention relates to laminatingfilms having a compliant surface having a hardness of 60 Shore A or lessfor laminating a micro-featured and nano-featured surface.

The non-tacky compliant surface of the laminating film is capable offorming upon contact a dry adhesive bond with the non-tackymicro-featured and nano-featured surface to be laminated. Therefore,when the compliant surface is brought into physical contact with thefeatured surface, a dry adhesive bond instantaneously forms. As thisprocess takes place at room temperature, the featured surface may belaminated at room temperature, which is advantageous compared to someother laminating films. Further, the laminating film may advantageouslybe applied without pressure; a simple swipe with one hand beingsufficient to effect the lamination. Consequently, the use of laminatingequipment is not necessary. Further, in contrast to the hot meltlamination films of the prior art, the thickness of laminating film ofthe invention is not limited by heat transfer constraints. Finally, allof this facilitates the use of cheaper raw materials for the variouslayers of the laminating film as discussed below.

As explained with regard to the dry adhesive above, the dry adhesion is,in many embodiments, reversible. In such case, the laminating film withthe compliant surface can be detached from the micro-featured andnano-featured surface in a non-destructive manner. The detachmentprocess will be residue-free when the tear strengths of the compliantsurface and micro-featured and nano-featured surface are bothsufficiently high. Thus, if desired, a laminating film removed from amicro-featured and nano-featured surface may be re-applied to the sameor another micro-featured and nano-featured surface. In embodiments, theadhesion is completely reversible, meaning that the laminating film canbe repeatedly laminated on and delaminated from one or moremicro-featured and nano-featured surface. In embodiments, the adhesionis partially reversible, meaning that the laminating film can belaminated on and delaminated from one or more micro-featured andnano-featured surface only a certain number of times or that amicro-featured and nano-featured surface can be laminated anddelaminated by one of more laminating film only a certain number oftimes. An advantage of this reversibility (even the limitedreversibility) is that the laminating film may be applied, removed,adjusted, and/or reused.

The micro-featured and nano-featured surface to be laminated is of thesame nature as the above-described micro-featured and nano-featuredsurface. To simplify discussion, the description of this material is notrepeated here. In embodiments however, the micro-featured andnano-featured surface is advantageously paper-based, such as theabove-described inkjet photo paper. It is an advantage of the presentlaminating film that it can be used on popular commercially availableinkjet papers.

In many embodiments, the featured surface bears information or an imagethat is to be preserved by lamination.

The compliant surface of the laminating film is of the same nature asthe compliant surface described above. To simplify discussion, thedescription of this material is not repeated here. In an embodiment, thecompliant surface is made of an elastomer and/or elastomeric compositionhaving hardness less than 60 Shore A such as those of Table I and IIabove.

In embodiments, the laminating film comprises of a plurality of layers.A person of ordinary skills in the art will be able to select the numberof layers in the film in accordance with its desired functionality. Inan embodiment, the laminating film comprises a base film on which acompliant layer is located. In embodiments, the compliant layer iscoated or extruded on the base film.

In embodiments, the base film may comprise or be made of, for example,of PET, PP, PE (polyethylene) or any transparent plastic film. Inembodiments, the base film may comprise or be made of a polymer mainlycomprising, but not being limited to, polypropylene (PP), polyethyleneterephthalate (PET), polybutylene terephthalate, polyethyleneterephthalate-isophthalate copolymers, polyamide, polyimides,triacetylcellulose, acrylic resins, polyether sulfones, polyvinylchlorides, vinyl chloride-vinylidene chloride copolymers, polystyrene,and/or polystyrene copolymer. A person of ordinary skills in the artwill appreciate that these and other polymers may be employed for thebase film either alone or as a blend. For example, transparentpolymer(s) may be used if the surface to be laminated has visualinformation that may need to be displayed such as a printed image.Alternatively, translucent and/or non-transparent polymer(s) may beselected if the visual information on the substrate to be protected doesnot need to be displayed.

The base film may further comprise an UV absorber. In an embodiment,this UV absorber is incorporated in the base film during its extrusion.This UV absorber will retard fading of the printed images due to UVrays. Non limiting examples of UV absorber include benzophenone,oxanilide, benzotriazole, hydroxyphenyltriazine and mixtures thereof.

Non-limiting examples of benzophenone include 2,4-dihydroxybenzophenone,2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-(octyloxy)bezophenone,2,2′,4,4′-tetrahydroxybenzophenone,2-hydroxy-4-methoxy-5-sulfobenzophenone and mixtures thereof.

Non-limiting examples of oxanilide include 2,2′,4,4′ tetra nitrooxanilide and/or N,N′-diphenyloxamide and mixtures thereof.

Non-limiting examples of benzotriazole and hydroxyphenyltriazinesinclude 2-(2-hydroxy-5-methylphenyl)benzotriazole,2-(2H-benzotriazol-2-yl)-4-(1,1′,3,3′-tetramethylbutyl)phenone,2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenone,2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol,2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chloro-2H-benzotriazole,2-[2H-benzotriazol-2-yl]-4,6-bis(1-methyl-1-phenylethyl)-phenol,2-[3,5-di-tert-butyl-2-hydroxyphenyl]-2H-benzotriazole,2,2′-methylenbis[6-(2H-benzotriazol-2-yl)-4-(1,1′,3,3′-tetramethylbutyl)phenol],2-(3-sec-butyl-5′tert-2-hydroxyphenyl)-2H-benzotriazole and mixturesthereof.

In an embodiment, the base film comprises one or more additives. Thesemay, for example, improve the lightfastness of an image printed on thesurface to be laminated. For example, hindered amines light stabilizer(HALS) may be employed to scavenge free radicals generated during thethermal oxidation process. In another example, antioxidants may beemployed to terminate the oxidation reactions that may take place duringthe thermal oxidation process.

As may be appreciated from the foregoing, light stabilizers may beemployed directly and/or in combinations to prevent and/or minimize theeffects of photo oxidation. A person of ordinary skills in the art willbe able to select any light stabilizer or combination thereof dependingupon the polymer selected for base layer and/or printed image on thesurface to be laminated.

In an embodiment, there is an adhesion promoting layer between the basefilm and the compliant layer to promote the adhesion between these twoelements. This adhesion promoting layer may also provide reactive sitesallowing the base film to form cohesive bonds with the compliant layer.In an embodiment, the adhesion promoting layer comprises an UV absorbersuch as those described above.

In embodiments, the adhesion promoting layer comprises a polyethyleneresin modified with anhydride functional groups. In a non-limitingexample, Admer QF551 E available from Mitsui Chemicals, Tokyo, Japan maybe employed as this polyethylene resin. Other adhesion promoting resinsare commercially available including for example Bynel® from E.I. duPont, Plexar® from Equistar, and Amplify™ from the Dow Chemical Company.

In embodiments, the adhesion promoting layer comprises an acid-modifiedpolypropylene resin. Non-limiting examples of the acid component of thisresin are carboxylic acid and/or anhydrides of unsaturated carboxylicacids. In embodiments of the acid-modified propylene polymer, the rangeof acid component may be from about 0.05 weight percent to about 0.45weight percent. In an embodiment, the acid-modified propylene resin maybe a propylene-α-olefin copolymer. In embodiments, the acid-modifiedpropylene resin may further comprise an ethylene-vinyl acetate copolymerand/or its acid-modified derivatives or an ethylene-(meth) acrylic estercopolymer and/or its acid-modified derivatives.

In further embodiments, the compliant surface can be covered by aprotective film, which protects the laminating film until it is used. Inembodiments, the protective film is an (advantageously inexpensive)polymeric material, such as polyethylene, polypropylene,polyvinylchloride, ethylene vinyl acetate, and/or amorphous polyethyleneterephthalate.

FIG. 13 shows a laminating film in accordance with an embodiment of theinvention. In this figure, the laminating film comprises base film 402and a compliant layer 404.

FIG. 14 shows a four-layer laminating film in accordance an embodimentof the invention. The laminating film again comprises base film 402 anda compliant layer 404. There is an adhesion promoting layer 406 betweenthe base film 402 and the compliant layer 404. Further, the compliantlayer 404 is covered by a protective film 408.

Any known art may be employed in the fabrication of the laminating film.Non-limiting examples of methods for manufacturing the laminating filmis to prepare layers of uniform thickness by co-extrusion orco-stretching. Coating methods can also be used for certain layers.

Boards, Everyday and Industrial Adhesives, Games and Toys and VariousOther Applications

As the skilled person will appreciate, there is a myriad of applicationsfor the above dry adhesive and its dry self-adhesive and micro-featuredand nano-featured surface embodiments. In fact, their commercial andindustrial applications are limited only by the imagination.Non-limiting examples of these possible applications will be discussedbelow.

The applications for dry adhesive are numerous. Non-limiting examples ofapplications include adhesives backed products, removable adhesives,sewing and craft, straps and strips, lawn and garden, holidays tie-down,button replacement, diaper tabs, stationary and paper arts, memo boards,albums, temporary carpet protection, toys, automotive, electronics,construction, industrial adhesive, apparel, footwear, display,packaging, material handling, military, health care, agriculture,aerospace, sports, recreation, surface protection, sealing, maskingtapes, etc.

The dry adhesive (including the dry self-adhesive) may be employed incurrent applications where conventional adhesive materials and fasteners(such as for example, various glues and hook-and-loop fasteners) aretypically used. In fact, the invention is particularly useful inapplications requiring blind fasteners (i.e. where holes or similardamage is NOT produced on the objects to be adhered together) arerequired and/or where a reversible attachment is desired.

In particular, there are very numerous applications for embodiments:

-   -   where the dry self-adhesive is provided with a conventional        adhesive backing for adhering the dry self-adhesive to one or        more substrates and thus allowing reversibly adhering these        various substrates to each other; or    -   where the micro-featured and nano-featured surface and the        compliant surface are provided with a conventional adhesive        backing allowing adhering the compliant surface to a first        substrate and the micro-featured and nano-featured surface to a        second substrate and reversibly adhering the first substrate to        the second substrate.

For example, such embodiments can be used to replace fasteners of the3M™ Dual Lock™ type and of the Velcro™ (hook and loop) type as well asmounting putty in many of their applications.

Applications include mounting signage or ads or securing panels (forexample, on walls), assembling displays, assembling various parts of anobject (in industrial manufacturing, in toys, etc.), andmounting/keeping decorative elements in place. Another application is tosecure various objects in place at home, at the office and also in spacewhere zero-gravity conditions causes all objects to float if not securedin place.

The invention could be use in clothing and shoes to replacehook-and-loop fasteners, snap-on fasteners, button and even zippers.

Other uses include holding together cables and use as diaper's closures.

Another use is in boards such as advertisement billboards like those onwalls and along motor roads. In embodiments, the billboard surface is amicro-featured and nano-featured surface, for example the micro-featuredand nano-featured aluminium. A sheet has an ad or another image printedon its front, while its backside bears a layer of compliant material soas to form a compliant surface. In embodiments, the sheet is a plasticsheet. For example, it can be a vinyl sheet such as a PVC sheet, a PETsheet or a sheet made of another polymer. The layer of compliantmaterial may be, in embodiments, from 5 to 50 μm thick. The ad or imagecan be inkjet printed using solvent or UV based inks. In embodiments,where these inks are pigments and waterfast, it is not necessary toprotect the image with an overcoat. In other embodiments, such aprotective overcoat is provided. In use, the sheet is attached to theboard by dry adhesion, thus no nails, glue or screws are needed. Thesheet can be pulled away from the board as needed (e.g. for alignmentpurposes or for changing the ad).

Yet another use for mounting displays (ads and the like) on glass. In anembodiment, a compliant layer is adhered to one side of the glass byconventional means for example a transparent (preferably invisible)regular adhesive. Then, a micro-featured and nano-featured surface ofthe display (for example a printed ad) is contacted with the compliantlayer to effectively mount the display on the glass. In embodiments, thecompliant layer is transparent and the micro-featured and nano-featuredsurface bears an image that is displayed through the glass.Advantageously, the display is two-sided and bears images for display onboth its sides (at least one side of the display having, of course, amicro-featured and nano-featured surface). In this case, both images arevisible while the display is invisibly fastened on the glass. Thedisplay can be easily be removed and replaced by another display. Thiswould be useful in commercial settings. This could also be a toy forchildren with the display being pre-made letters or various images. Inthis case, the display could also be a children's drawing on a substratewith a micro-featured and nano-featured surface (for example inkjetphoto paper).

Another application of the dry adhesive is for bulletin boards andsimilar objects. In an embodiment, a board with a micro-featured andnano-featured surface is provided. Various objects with a compliantsurface can be reversibly displayed on the board. Objects with compliantsurface can be three-dimensional. They can also be paper or plasticsheets backed with a compliant surface. Both the paper and plasticsheets are writable and/or bear writings and/or images. In anembodiment, the plastic sheets are writable and erasable when used, forexample, with dry erase markers.

In a similar embodiment, a board with a compliant surface is providedand objects with a micro-featured and nano-featured surface can bereversibly displayed on it. Objects with micro-featured andnano-featured surface can be three-dimensional. They can also be sheetsof various materials. They can be any of the above-described papersheets with micro-featured and nano-featured surfaces. They can also beplastic or metal sheets with a micro-featured and nano-featured surfacesuch as those discussed above. These can be writable and/or bearwritings and/or images or they can be fronted with a substrate that iswritable and/or bear writings and/or images (the backside being themicro-featured and nano-featured surface that will adhere to thecompliant surface of the board).

In other embodiments, both the board and the objects have a dryself-adhesive surface. The objects may be three-dimensional or they canbe sheets of various materials. These can be writable and/or bearwritings and/or images or they can be fronted with a substrate that iswritable and/or bear writings and/or images (the backside being the dryself-adhesive surface that will adhere to the dry self-adhesive surfaceof the board).

These boards can be used in a variety of settings. They can be used todisplay ads, messages, menus in restaurants, or various other notes (forexample at home or in a workplace, e.g. an office), etc. In embodiments,the objects are similar to sticky notes.

In embodiments, the board can be an entire wall or a partition wall orboard on which various objects (art pieces, ads, posters such as thoseused in conferences) can be displayed.

The above board and objects can be provided separately or together as akit. Therefore, the present invention covers them together as well asseparately.

In other applications, the dry adhesive may be employed in circuitboards. Various adhesives are typically used when manufacturing circuitboards; these can be, for example, epoxies and tapes. The dry adhesivemay replace such materials.

In an embodiment of the invention, there is provided a game or toycomprising the above dry adhesive, including its dry self-adhesiveembodiment. The game or toy can be destined to adults, teenagers and/orkids.

In embodiments, the game or toy is a dart game, wherein themicro-featured and nano-featured surface bears an image of a target andwherein the compliant surface is a surface of a tip of a dart, the tipbeing made of a compliant material.

This game can be played in the same manner as conventional dart gamesare played. Additionally, the darts can be replaced by projectiles ofany suitable form, for example, balls or other. The darts can be thrownby hand or they may be projected from a toy gun such as that for childuse or a more effective gun, such as that used for practicing paintball.Therefore, in embodiments, the game or toy of the invention is a gamefor practicing and improving hand shooting skills and/or gun shootingskills.

In yet other embodiments, the game or toy is a shooting game, whereinthe nano- and micro-featured surface is embedded in a piece of clothing,and wherein the compliant surface is a surface of a projectile.

In this game, the projectile may be a dart, a ball or any other suitableprojectile. The projectile may be projected from a toy gun such as thatfor child use or a more effective gun, such as that used for practicingpaintball. In embodiments, the clothing is a training jersey, a pair ofpants, a helmet, protective eyewear, a suit and the like. For example,the clothing may be a suit such as that worn for practicing paintball.This game can be similar to that marketed by Hasbro™ under the trademarkNerf Dart Tag™.

In other embodiments of the game or toy, the micro-featured andnano-featured surface bears an image missing a part at a locationthereof and the compliant surface is on the backside of a substratebearing an image of the missing part, the game comprising correctlyplacing the missing part at said location. In embodiments, the image onthe micro-featured and nano-featured surface is missing many parts andthe compliant surface is on the backside of many substrates each bearingone of these missing parts. In an embodiment, both the surface bearingan image missing one or more part and the surface of the backside of thesubstrate bearing an image of the missing part are dry self-adhesivesurfaces. In these embodiments, both the micro-featured andnano-featured surface and the substrate with a compliant surface on itsbackside can be replaced by a dry self-adhesive surface. Similar toyscan take the form of puzzles or art work.

This game or toy can be a game for very young children to learn thedifferent parts of an object. It can be a puzzle. It can also be a “Pinthe Tail on the Donkey” type of game where a player tries to correctlyplace the missing part(s) on the image on the nano- and micro-featuredsurface without looking at it.

In other embodiments, the game or toy is a building set where some ofparts have a micro-featured and nano-featured and some other parts havea compliant surface and both types of parts are used to build an object,for example a model of a vehicle or a building. In embodiments, some orall of the parts of this building set bear both types of surfaces sideby side and/or on various sides thereof. In these embodiments, both themicro-featured and nano-featured surface and the compliant surface canbe replaced by a dry self-adhesive surface.

In another embodiment, the game or toy is an art and craft set wheresome of parts have a nano- and micro-featured surface and some otherparts have a compliant surface and both types of parts are used to buildan art and craft project. In embodiments, some or all of the parts ofthis art and craft set bear both types of surfaces side by side and/oron various sides thereof. In these embodiments, both the micro-featuredand nano-featured surface and the compliant surface can be replaced by adry self-adhesive surface.

In other embodiments, the game or toy is a board (or more generally aplay surface, or even a book or album) with accompanying cards orobjects to be placed on the board, the board bearing on its face one ofthe nano- and micro-featured surface and the compliant surface and thecards or objects bearing on their backside the other of the nano- andmicro-featured surface and the compliant surface. In these embodiments,both the micro-featured and nano-featured surface and the compliantsurface can be replaced by dry self-adhesive surfaces.

This board can be portable and used for example on a table or on thefloor. The board can also be fixed on a wall. In all cases, the boardcan bear various images and writings.

In embodiments, the board is replaced by a book or a “sticker” album onwhich cards and/or objects can be attached and detached as a story istold or as they are collected.

The cards can, for example, bear words or letters. In this case, theboard/book can bear lines for placing the words and letters. This toycan thus be used for teaching a child to read. A version with numbersand mathematical operators can be used for teaching mathematics.

The cards can be in the shape of various pieces of clothing and fashionaccessories. In this case, the board can bear the image of a figure tobe clothed in a dress up game.

The cards can also be puzzle pieces and the board may receive thesepieces. This would allow putting the puzzle away when not playingwithout losing puzzle pieces and without having to put the puzzle piecesin a box. This would also allow hanging the puzzle from a wall.

Instead of or in conjunction with cards, objects can be used on theboard. For example, cards with the names of children can be placed onthe board and objects in the shape of cars, stars, and the like can beplaced next to a child's name, for example, as a reward for goodbehavior or for succeeding in a task such as a learning task.Alternatively, the board can bear a child schedule and a child figurine(or another card or object representing the child) can be moved on theboard according to the time of day. In another embodiment, the board isa game board (e.g. a chess board) with accompanying objects (e.g. chesspieces) that will adhere to the board. This allows playing a game on theboard while the board is not supported by a table for example in a car,in a waiting room, etc.

In yet other embodiments, the game is a set or vehicle for playing withfigurines (human or other). For example, a garage set for playing withcars, a firefighter truck with firefighters and their equipment, abuilding set with construction materials and human figurines, a farm setfor playing with animal and human figurines, and the like. Various partsof the set and the figurines can have a nano- and micro-featured surfaceand/or a compliant surface, which allows their dry adhesion. Forexample, the working end of a crane can have a nano- and micro-featuredsurface to which mock construction materials with a compliant surface orentirely made of a compliant material can adhere. In another example, anaction figure is held down into a toy car through dry adhesion between anano- and micro-featured surface and a compliant surface. In theseembodiments, both the micro-featured and nano-featured surface and thecompliant surface can be replaced by a dry self-adhesive surface.

It will be clear to the skilled person that the invention can replaceglue, magnets and/or Velcro™ in many instances where they are used intoys and games.

It will also be clear that in many instances above, the nano- andmicro-featured surface and the compliant surface can swap positionwithout affecting the working of the game or toy. It will also be clearto the skilled person that in many instances the nano- andmicro-featured surface and the compliant surface can both be replaced bydry self-adhesive surfaces even when it is not explicitly mentioned. Thepresent application intends to cover such variations.

Herein, “about” has its usual meaning. It can, for example, mean more orless 5% of the numerical value qualified by this term.

Herein, “comprising” is an open-ended term meaning “including, but notbeing limited to”.

Other objects, advantages and features of the present invention willbecome more apparent upon reading of the following non-restrictivedescription of specific embodiments thereof, given by way of exampleonly with reference to the accompanying drawings.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention is illustrated in further details by the followingnon-limiting examples.

Examples 1 to 5 Micro-Featured and Nano-Featured Surfaces

The surface of aluminum sheets of a thickness of about 0.30 mm weretreated according to process 200 as described above using variousconditions. These different process conditions are shown in Table IIIbelow.

TABLE III Processing EXAMPLES Steps Conditions 1 2 3 4 5 Degreasing NaOHand sodium Yes Yes Yes Yes Yes gluconate Mechanical Nylon brush & pumiceNo No Yes No Yes Graining stone powder Electrolytic HCl (6.00 g/L) 1,000Graining HCl (8.00 g/L) & 1,250 270 276 (C/dm²) CH3COOH (16.0 g/L) HNO₃(10 g/L) 160 Anodization H₂SO₄ (140 g/L) 5.60 5.60 5.60 5.60 (A/dm²)H₃PO₄ (160 g/L) 7.00 Functionalization NaH₂PO₄ (50.0 g/L) & Yes Yes YesNaF (0.80 g/L) Vinyl phosphoric and Yes acrylic copolymer (0.30 g/L)Oxide weight 2.70 1.80 2.70 2.20 (g/m²) R_(a) (μm) 0.65 0.52 0.27 0.420.60 RS_(m) (nm) 24 26 220 44 200

In Example 1, the surface of the aluminum sheet was pre-treated bydegreasing, micro-featured by electrolytic graining in a 6.0 g/L HClsolution with 1,000 C/dm² of alternating current density, nano-featuredby electrolytic anodization in a 140 g/L H₂SO₄ solution with 5.60 A/dm²of direct current density, and functionalized with a 50.0 g/L NaH₂PO₄and 0.80 g/L NaF solution. FIG. 1 shows a scanning electron micrograph(SEM) of the treated aluminum substrate where the micro-features andnano-features selectively created on the aluminum surface are visible.For this surface, the R_(a) is 0.65 μm and the RS_(m) is 24 nm.

In Example 2, the surface of the aluminum sheet was pre-treated bydegreasing, micro-featured by electrolytic graining in a 8.0 g/L HCl and16.0 g/L CH₃COOH solution with 1,250 C/dm² of alternating currentdensity, nano-featured by electrolytic anodization in a 140 g/L H₂SO₄solution with 5.60 A/dm² of direct current density, and functionalizedwith a 50.0 g/L NaH₂PO₄ and 0.80 g/L NaF solution. FIG. 2 shows ascanning electron micrograph (SEM) of the treated aluminum substratewhere the micro-features and nano-features selectively created arevisible. For this surface, the R_(a) is 0.52 μm and the RS_(m) is 26 nm.The oxide weight is 2.70 g/m².

In Example 3, the surface of the aluminum sheet was pre-treated bydegreasing, micro-featured by mechanical graining and by electrolyticgraining in a 8.0 g/L HCl and 16.0 g/L CH₃COOH solution with 270 C/dm²of alternating current density, nano-featured by electrolyticanodization in 160 g/L H₃PO₄ solution with 7.0 A/dm² of direct currentdensity, and functionalized with a 0.30 g/L vinyl phosphoric and acryliccopolymer solution. FIG. 3 shows a scanning electron micrograph (SEM) ofthe treated substrate where the micro-features and nano-featuresselectively created are visible. For this substrate, the R_(a) is 0.27μm and the RS_(m) is 220 nm. The oxide weight is 1.80 g/m².

In Example 4, the surface of the aluminum sheet was pre-treated bydegreasing, micro-featured by electrolytic graining in 10.0 g/L HNO₃solution with 160 C/dm² of alternating current density, nano-featured byelectrolytic anodization in 140 g/L H₂SO₄ solution with 5.6 A/dm² ofdirect current density. FIG. 4 shows a scanning electron micrograph(SEM) of the treated substrate where the micro-features andnano-features selectively created are visible. For this substrate, theR_(a) is 0.42 μm and the RS_(m) is 44 nm. The oxide weight is 2.70 g/m².

In Example 5, the surface of the aluminum sheet was pre-treated bydegreasing, micro-featured by mechanical graining and by electrolyticgraining in a 8.0 g/L HCl and 16.0 g/L CH₃COOH solution with 276 C/dm²of alternating current density, nano-featured by electrolyticanodization in a 140 g/L H₂SO₄ solution with 5.6 A/dm² of direct currentdensity, and functionalized with a 50.0 g/L NaH₂PO₄ and 0.80 g/L NaFsolution. For this treated substrate, R_(a) is 0.60 μm and RS_(m) is 200nm. The oxide weight is 2.20 g/m².

Example 6 Micro-Featured and Nano-Featured Surface

A biaxially oriented polyethylene terephthalate film (PET) having athickness of 30 μm and containing 30% Zeolite A (mean particle size 1.0μm) and 5% calcium carbonate (mean particle size 2.0 μm) was extruded260° C. from a twin screw extruder. It was then stretched to a 3:1 ratioat 130° C. The stretched film was then dipped in a 2M hydrochloric acidsolution at 40° C. for 24 hours to partially dissolve the calciumcarbonate, which created micropores on the surface. The treated film wasthen washed with water and dried in a hot air oven at 110° C. It wasthen dipped in an aqueous polymeric solution containing 5% of silicacolloid particles (Ludox HS40 and Ludox SK, available from Dupont, USA),and then dried in a hot air oven at 120° C. This created nanopores onthe surface. For this surface, the R_(a) is about 0.50 μm and RS_(m) is400 nm. FIG. 5 shows a scanning electron micrograph of the treated PETfilm.

Observations Concerning Examples 1 to 6

Treated surfaces according to the invention, including those of Examples1 to 6, were tested. Donut-shaped objects and thread-like objects madeof a compliant material (KRATON® D1161 B Polymer) were used. Theseobjects were non-tacky; they did not adhere to the hands of the user.The treated surfaces were also non-tacky; the user could easily rub themwithout feeling any tackiness.

When placed or thrown on the treated surfaces, the compliant objectsadhered to them. The adhesion was sufficiently strong to allow movingthe treated surfaces (turning them on their side, placing themupside-down, facedown, etc.) without the objects falling down. It wasnecessary to pull on of the objects to get them off the treatedsurfaces. In some cases, a significant force had to be applied for thecompliant object to become separated from the treated surface.

In most cases, the compliant objects did not leave any residue on thetreated surfaces when separated from it. In a few case, a very slightimprint was visible on the treated surfaces.

FIG. 15 is a picture showing three compliant donut-shaped objectsadhering to a vertically held aluminum substrate with a surfaceaccording to the invention. This surface had a R_(a) of 0.51 μm and aRS_(m) of 65 nm and had been functionalized with phosphate fluoride(PF). FIG. 16 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on the same substrate as FIG. 15.This time, the substrate is held facedown. It can be seen that theobjects did not fall.

FIG. 17 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on another aluminum substrate witha surface according to the invention. FIG. 18 is a photograph showingthe adhesion of the same four donut-shaped objects as well as onethread-like object made of a compliant material on the same substrate asFIG. 17. This time, the substrate is held facedown. It can be seen thatthe objects did not fall.

FIG. 19 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on a vertically held substrate witha surface according to the invention. This substrate was the PETsubstrate incorporating zeolite described in Example 6 above. FIG. 20 isa photograph showing that the substrate of FIG. 19 bearing fourdonut-shaped objects can be supported by holding only one of thedonut-shaped objects. Even when shaking, the surface remained adhered tothe held object. FIG. 21 is a photograph showing one of the inventorspulling on an object to remove it from the substrate of FIGS. 19 and 20.It was necessary to pull the objects; otherwise they would remainadhered to the surface.

FIG. 22 is a photograph showing the adhesion of four donut-shapedobjects made of a compliant material on another vertically heldsubstrate with a surface according to the invention. This was analuminum surface with R_(a)=0.50 μm, RS_(m)=26 nm, a phosphate fluoridetreatment and an aluminum oxide layer of 2.4 μm.

Videos (#12052011018, 12052011019, 12052011020, 12052011021,12052011022, and 12052011023) of some tests on various substrates withsurfaces according to the invention were made.

Comparative Example 1

It was observed that the compliant objects did not adhere at all to the(untreated) backsides of the treated surfaces of Examples 1 to 6.

The compliant objects did not adhere to an aluminum surface comprisingmicropores only, which was prepared by graining and sand blastingtechniques. Similarly, the compliant objects did not adhere to analuminum surface comprising nanopores only, which was prepared byanodization.

Example 7 Self-Adhesive

An anodized aluminum sheet (size 20 cm×30 cm, thickness of 0.15 mm)comprising micro-features and nano-features (R_(a) 0.25 μm and RS_(m) 26nm) was provided in accordance with the above. The sheet was dipped intoan ethanol solution containing 5 g/L of triethoxysilane and a trace ofhydrochloric acid at room temperature. The sheet was then dried in a hotair oven at 80° C. for 3 minutes. A heat curable silicone elastomercomposition (QLE1031, available from Quantum Silicones, Va., USA) wasscreen printed on the treated aluminum sheet to form a pattern of rounddots having a diameter about 2.0 mm. The spacing between the round dotswas about 4.0 mm. The sheet was then cured at 150° C. for 20 minutes ina hot air oven to produce surface tack-free silicone compliant dotshaving a thickness of about 30 μm and which strongly adhered to theporous aluminum sheet. The hardness of the silicone compliant dots wasmeasured and was found to be about 25 Shore-A.

A second aluminum sheet was prepared in a similar way.

The first and second aluminum sheets were pressed face-to-face. Theystrongly adhered to each other and could be peeled apart withoutdamaging them, i.e. without delaminating the silicone compliant dots.

Example 8 Self-Adhesive

An anodized aluminum sheet (the same as in Example 7) was used. Half ofit was left as is while the other half was screen printed with asolution of ethylene-butadiene-styrene elastomer (hardness 27 Shore-A,available from Mylan Group, Travinh, Vietnam) in toluene to form apattern of round dots. A 110 mesh screen was used to produce dots ofabout 790 micrometers with spacing of about 870 micrometers. It was thendried using hot air at 80° C.

Both halves of the dry self-adhesive aluminum sheet thus produced werecut apart and placed face to face. The halves adhered very well to oneanother. They were subsequently peeled apart without delaminating thecompliant dots. This adhering/peeling process was repeated several timeswith good adhesion and easy peeling.

FIG. 23 (A to F) shows static images drawn from a video (MVI_9987). Theyshow various steps of a test of the dry adhesive aluminum sheet. The dryadhesive aluminum sheet is shown in FIG. 23A. It was non-tacky; forexample the experimenter could easily rub his fingers on it. The toppart of the sheet was non-porous, while the bottom part was porous, i.enot coated with the elastomer. Both halves were cut apart as shown inFIG. 23B. A part of one of the halves was folded to produce a make-shifthook in FIG. 23C. Both halves were placed face to face as shown in FIG.23D. The adhesion was so good that a heavy Aldrich catalog could besupported by the half with the makeshift hook while holding only theother half (see FIG. 23E). Finally, both halves were easily pulled apartas shown in FIG. 23F. This process was repeated several times with thesame good success.

Example 9 Self-Adhesive

A dry self-adhesive sheet having a surface comprising porous areas andcompliant areas was prepared by screen printing a heat curable siliconeelastomer composition (QLE1031, available from Quantum Silicones, Va.,USA) on an inkjet photo paper (Ultra Premium Photo Paper Glossy,available from Epson) to form a pattern of round dots having a diameterof about 2.0 mm. The spacing between the round dots was about 4.0 mm.The sheet was then cured at 150° C. for 20 minutes in a hot air oven toproduce surface tack-free silicone compliant dots having a thickness ofabout 30 μm that strongly adhered to the porous paper sheet. Thehardness of the silicone compliant dots was measured at about 25Shore-A.

A second paper sheet was prepared in the same way. The first and seconddry adhesive sheets were pressed face-to-face. They strongly adhered toeach other and could be peeled apart without delaminating the siliconecompliant dots.

FIG. 24 (A to D) shows static images drawn from a video (MVI_9982). Theyshow various steps of a test of the dry adhesive sheet. The dry adhesivesheet was non-tacky and the experimenter could easily rub his fingers onit (FIG. 24A). The sheet was folded around a pen and a cord holding aheavy Aldrich catalog and partly folded onto itself as shown in FIG.24B. The adhesion was so good that the heavy Aldrich catalog could besupported by the folded sheet while the experimenter only held one sideof the folded sheet (see FIG. 24C). Finally, the sheet was easilyunfolded (see FIG. 24D). This process was repeated several times withthe same good success.

Example 10 Self-Adhesives

A dry self-adhesive sheet having a surface comprising porous areas andcompliant areas was prepared by screen printing a toluene solutioncontaining an ethylene-butadiene-styrene elastomer (harness 27 Shore-A,available from Mylan Group, Travinh, Vietnam) on an inkjet photo paper(Ultra Premium Photo Paper Glossy, available from Epson) to form apattern of round dots. A 110 mesh screen was used to produce dots ofabout 790 micrometers with spacing of about 870 micrometers. The sheetwas then dried using hot air at 80° C.

A second dry self-adhesive sheet was prepared in the same way. The firstand second dry adhesive sheets were pressed face-to-face. They stronglyadhered to each other and could be peeled a part without delaminatingthe silicone compliant dots.

FIG. 25 (A to E) shows static images drawn from a video (MVI_9984). Theyshow various steps of a test of the dry adhesive sheet. The dry adhesivesheet (FIG. 25A) was non-tacky and the experimenter could easily rub hisfingers on it. The sheet was folded around a pen and a cord holding aheavy Aldrich catalog and partly folded onto itself as shown in FIGS.25B and C. The adhesion was so good that the heavy Aldrich catalog couldbe supported by the folded sheet while the experimenter only held oneside of the folded sheet (see FIG. 25D). Finally, the sheet was easilyunfolded (see FIG. 25E). This process was repeated several times withthe same good success.

Example 11 Self-Adhesives

A polysulfone membrane sheet (pore size 0.45 μm, thickness of 200 μm,available Sigma Aldrich, Ontario, Canada) was screen printed to form apattern of square dots with an aqueous composition containing 35% ofpolyvinyl alcohol (Celvol 523, available from Air Products, USA), 60% ofalumina particles (Cab-O-Sperse PG008, available from Cabot, USA) and 5%of boric acid. The sheet was then dried with a hot air at 80° C. Then atoluene solution containing an ethylene-butadiene-styrene elastomer(hardness 27 Shore-A, available from Mylan Group, Travinh, Vietnam) wasscreen printed to form a pattern of round dots on the surface of thepreviously printed polysulfone membrane without overlapping with thesquare dots. A 110 mesh screen was used to produce dots of about 790micrometers with spacing of about 870 micrometers. The sheet was thendried using hot air at 80° C. The porous square dots and non-tackycompliant round dots adhered very well to the polysulfone membranesheet.

A second polysulfone membrane sheet was prepared in the same way. Thesetwo printed sheets adhered very well to each other when placedface-to-face. They were also easily peeled apart without delaminatingthe square and round dots.

Examples 12-14 Laminating Films

Table IV shows the raw materials employed in Examples 12-14.

Elasto-100A A mixture of low and high molecular weight aminopropylterminated siloxane dimethyl polymers, available from Mylan Group,Travinh, Vietnam. MW 10,000 g/mol Elasto-100B A mixture of di-isocyanateand poly-isocyanate compounds, available from Mylan Group, Travinh,Vietnam. Sabic BC112 Polyethylene terephthalate resin, available fromSaudi Basic Industries Corporation, Kingdom of Saudi Arabia. Tinuvin 360Ultraviolet absorber, available from BASF, Germany. Admer QF551EPolyethylene resin modified with anhydride functional group, availablefrom Mitsui Chemicals, Tokyo, Japan PET-360 A two layers plastic filmcomprising a 50 μm polyethylene terephthalate layer (97% Sabic BC112 and3% Tinuvin 360) and a 20 μm anhydride functionalized polyethylene (AdmerQF5551) layer, which were co-extruded on a Reifenhauser thermoformingline, available from Mylan Optoelectronics, Travinh, Vietnam. KratonD1161 Styrene-butadiene-styrene copolymer, available under trade nameKraton D1161 from Kraton Polymers, Houston, TX 77032

Example 12

A polyethylene terephthalate (PET) laminating film was produced bycoating a mixture of Elasto-100A (80% by weight) and Elasto-100B (20% byweight) on a PET-360 substrate using a wire-wound rod coating station ona coating line (Model Combi-Horizontal, available from NordmeccanicaSPA, Piacenza, Italy) at a speed of 100 meter per minute. The coatedfilm was cured using hot air at 120° C. to give an excellent clarityPET-based laminating film bearing a 20 μm tack-free elastomeric layer.The hardness of this compliant layer was measured to be 32 Shore A. Theresulting PET laminating film adhered very well when laminated at roomtemperature on a printed sheet of Epson™ Ultra Premium Photo PaperGlossy.

Example 13

A polyethylene terephthalate laminating film was produced similarly toExample 1 with a different ratio between Elasto-100A (65% by weight) andElasto-100B (35% by weight) to give an excellent clarity PET-basedlaminating film bearing a 20 μm tack-free elastomeric layer. Thehardness of this compliant layer was measured to be 43 Shore A. Theresulting PET laminating film adhered very well when laminated at roomtemperature on a printed sheet of Epson™ Ultra Premium Photo PaperGlossy.

Example 14

A polyethylene terephthalate laminating film was produced by extruding aKraton D1161 copolymer at 175° C. onto a PET-360 substrate using anextrusion laminating line (Lamicor, available from Reifenhauser,Troisdorf, Germany). This produced an excellent clarity PET-basedlaminating film with a 20 μm tack-free elastomeric layer. The hardnessof the compliant layer was measured to be 37 Shore A. The resulting PETlaminating film adhered very well when laminated at room temperature ona printed sheet of Epson™ Ultra Premium Photo Paper Glossy.

Example 15 Dart Board and Darts

A dart board was produced by creating micro-features and nano-featureson an aluminum sheet and then printing a target on the sheet. Darts weremade by placing a cap made of a compliant material (Kraton D1163) on theend of a foam stick.

FIG. 26 shows static images drawn from a video (DSCN4637). FIG. 27 showsstatic images drawn from other similar video (DSCN4639).

These figures show the use of the above dart board and associated darts.In FIG. 26A, a person is holding the dart board, the backside of whichis visible. In FIG. 26B, the front side of the dart board is shown. InFIG. 26C, a dart has been thrown and is now stuck on the dart board.FIG. 26D shows a close up of a dart stuck on the dart board. The dartcould easily be removed from the dart board.

In FIG. 27A, four (4) darts are stuck on the dart board after beingthrown; the dart board is held by a support. In FIG. 27B, a personeasily removes the four darts. FIG. 27C is a close up view of a dartshown the compliant cap on the end of the foam stick.

Although the present invention has been described hereinabove by way ofspecific embodiments thereof, it can be modified, without departing fromthe spirit and nature of the subject invention as defined in theappended claims.

1-20. (canceled)
 21. A dry adhesive assembly comprising a first articleand a second article, the first and second articles being capable of dryadhering to each other, wherein: the first article has a non-tackymicro-featured and nano-featured surface, said micro-featured andnano-featured surface having micropores and nanopores, said featured andnano-featured surface having a roughness average in amplitude (Ra)between about 0.2 μm and about 3.0 μm and a mean spacing of profileirregularities (RSm) between about 20 nm and about 2000 nm, and thesecond article has a non-tacky compliant surface having a hardness ofabout 60 Shore A or less, and upon contact of the micro-featured andnano-featured surface of the first article with the compliant surface ofthe second article, the compliant surface conforms with the topographyof the microporous and nano-porous surface resulting in a reversibleinterlock of the compliant surface in the micropores and nanopores ofsaid micro-featured and nano-featured surface, thus forming dry adhesivebond between the compliant surface and the micro-featured andnano-featured surface.
 22. The dry adhesive assembly of claim 1, whereinthe compliant surface has a hardness of about 45 Shore A or less. 23.The dry adhesive assembly of claim 1, wherein the compliant surface hasa hardness of about 25 Shore A or more.
 24. The dry adhesive assembly ofclaim 1, wherein the compliant surface has a hardness of between about25 and about 45 Shore A.
 25. The dry adhesive assembly of claim 1,wherein the second article is an object made of a compliant material.26. The dry adhesive assembly of claim 5, wherein the compliant materialis a silicon elastomer, a styrene-isoprene elastomer, astyrene-butadiene elastomer, a styrene-ethylene/butylene-styreneelastomer, a styrene-ethylene/propylene-styrene elastomer, anethylene-butadiene-styrene elastomer, a siloxane polymer, or apoly-isocyanate.
 27. The dry adhesive assembly of claim 1, wherein thesecond article comprises a layer of a compliant material alone or on asupport.
 28. The dry adhesive assembly of claim 7, wherein the supporthas a polymeric surface, a paper surface, or a metallic surface.
 29. Thedry adhesive assembly of claim 7, wherein the compliant material is asilicon elastomer, a styrene-isoprene elastomer, a styrene-butadieneelastomer, a styrene-ethylene/butylene-styrene elastomer, astyrene-ethylene/propylene-styrene elastomer, anethylene-butadiene-styrene elastomer, a siloxane polymer, or apoly-isocyanate.
 30. The dry adhesive assembly of claim 1, wherein thesecond article comprises multiples discrete areas of a compliantmaterial spaced apart on a support.
 31. The dry adhesive assembly ofclaim 10, wherein the support has a polymeric surface, a paper surface,or a metallic surface.
 32. The dry adhesive assembly of claim 10,wherein the compliant material is a silicon elastomer, astyrene-isoprene elastomer, a styrene-butadiene elastomer, astyrene-ethylene/butylene-styrene elastomer, astyrene-ethylene/propylene-styrene elastomer, anethylene-butadiene-styrene elastomer, a siloxane polymer, or apoly-isocyanate.
 33. The dry adhesive assembly of claim 1, wherein themicro-featured and nano-featured surface has a roughness average inamplitude (Ra) ranging between about 0.2 μm and about 1.5 μm.
 34. Thedry adhesive assembly of claim 13, wherein the micro-featured andnano-featured surface has a roughness average in amplitude (Ra) rangingbetween about 0.25 μm and about 1.5 μm.
 35. The dry adhesive assembly ofclaim 13, wherein the micro-featured and nano-featured surface has aroughness average in amplitude (Ra) ranging between about 0.2 μm andabout 0.7 μm.
 36. The dry adhesive assembly of claim 1, wherein themicro-featured and nano-featured surface has a mean spacing of profileirregularities (RSm) between about 20 nm and about 1500 nm.
 37. The dryadhesive assembly of claim 16, wherein the micro-featured andnano-featured surface has a mean spacing of profile irregularities (RSm)between about 20 nm and about 500 nm.
 38. The dry adhesive assembly ofclaim 17, wherein the micro-featured and nano-featured surface has amean spacing of profile irregularities (RSm) between about 20 nm andabout 100 nm.
 39. The dry adhesive assembly of claim 1, wherein themicro-featured and nano-featured surface is a metallic surface, a glasssurface, a paper surface, or a polymeric surface, said metallic surface,glass surface, paper surface and polymeric surface bearing microporesand nanopores.
 40. The dry adhesive assembly of claim 1, wherein saidfirst article comprises multiples discrete micro-featured andnano-featured areas spaced apart on a support.
 41. The dry adhesiveassembly of claim 20, wherein the support has a metallic surface, aglass surface, a paper surface, or a polymeric surface.